Veröffentlichungen von Autoren des Instituts für Informatik

2018 [ nach oben ]

• Nalepa, G.J., Baumeister, J.: SYNERGIES BETWEEN KNOWLEDGE ENGINEERING AND SOFTWARE ENGINEERING. Springer (2018).
  [ BibTeX ] [ URL ]
   
  @book{NalBau2017synergies, author = {Nalepa, Grzegorz J. and Baumeister, Joachim}, publisher = {Springer}, title = {SYNERGIES BETWEEN KNOWLEDGE ENGINEERING AND SOFTWARE ENGINEERING}, year = 2018 }

2017 [ nach oben ]

• Nguyen-Ngoc, A., Lange, S., Zinner, T., Seufert, M., Tran-Gia, P., Aerts, N., Hock, D.: Performance Evaluation of Selective Flow Monitoring in the ONOS Controller. 4th International Workshop on Management of SDN and NFV Systems (ManSDN/NFV). , Tokio, Japan (2017).
  [ Abstract ] [ BibTeX ]
   
  One of the benefits when network operators adopt the Software Defined Networking (SDN) paradigm is the ability to monitor the traffic in the network without an additional network management system. Usually, SDN controllers utilize OpenFlow statistics messages in order to regularly gather information about all flows in the network. However, using the same polling interval for all flows does not take into account the heterogeneity of real world traffic and thus results in an imbalance between monitoring accuracy and control plane overhead. In particular, frequent querying results in a high resource consumption at the controller. This work proposes a Selective Flow Monitoring (SFM) mechanism that allows administrators to classify flows according to their individual requirements in terms of monitoring frequency, e.g., less frequent polling of elephant flows and frequent polling of QoS sensitive VoIP connections. We compare the performance of the SFM mechanism with the default monitoring scheme in a testbed featuring the Open Network Operating System (ONOS) controller. In this context, the CPU utilization of the controller is used as performance indicator. After identifying relevant influence factors like the number of flows and switches in the network, we investigate the viability of the approaches in different scenarios. Finally, we provide guidelines regarding their choice.
  @inproceedings{info3-inproceedings-2017-20, abstract = {One of the benefits when network operators adopt the Software Defined Networking (SDN) paradigm is the ability to monitor the traffic in the network without an additional network management system. Usually, SDN controllers utilize OpenFlow statistics messages in order to regularly gather information about all flows in the network. However, using the same polling interval for all flows does not take into account the heterogeneity of real world traffic and thus results in an imbalance between monitoring accuracy and control plane overhead. In particular, frequent querying results in a high resource consumption at the controller. This work proposes a Selective Flow Monitoring (SFM) mechanism that allows administrators to classify flows according to their individual requirements in terms of monitoring frequency, e.g., less frequent polling of elephant flows and frequent polling of QoS sensitive VoIP connections. We compare the performance of the SFM mechanism with the default monitoring scheme in a testbed featuring the Open Network Operating System (ONOS) controller. In this context, the CPU utilization of the controller is used as performance indicator. After identifying relevant influence factors like the number of flows and switches in the network, we investigate the viability of the approaches in different scenarios. Finally, we provide guidelines regarding their choice.}, address = {Tokio, Japan}, author = {Nguyen-Ngoc, Anh and Lange, Stanislav and Zinner, Thomas and Seufert, Michael and Tran-Gia, Phuoc and Aerts, Nieke and Hock, David}, booktitle = {4th International Workshop on Management of SDN and NFV Systems (ManSDN/NFV)}, month = 11, title = {Performance Evaluation of Selective Flow Monitoring in the ONOS Controller}, year = 2017 }
• Seufert, M.: Unsupervised QoE Field Study for Mobile YouTube Video Streaming with YoMoApp. , 9th International Conference on Quality of Multimedia Experience (QoMEX), Erfurt, Germany (2017).
  [ BibTeX ]
   
  @presentation{info3-presentation-2017-4, address = {9th International Conference on Quality of Multimedia Experience (QoMEX), Erfurt, Germany}, author = {Seufert, Michael}, month = 6, title = {Unsupervised QoE Field Study for Mobile YouTube Video Streaming with YoMoApp}, year = 2017 }
• Seipel, D., Hanus, M., Abreu, S. hrsg: Declare 2017 – Conference on Declarative Programming. Institut für Informatik (2017).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  This technical report contains the papers presented at the Conference on Declarative Programming Declare 2017, in Würzburg, Germany, from September 19th to 22th, 2017. The joint conference consisted of the 21st International Conference on Applications of Declarative Programming and Knowledge Management INAP 2017, the 31st Workshop on Logic Programming WLP 2017, and the 25th Workshop on Functional and (Constraint) Logic Programming WFLP 2017. Declarative programming is an advanced paradigm for modeling and solving complex problems. This method has attracted increased attention over the last decades, e.g., in the domains of data and knowledge engineering, databases, artificial intelligence, natural language processing, modeling and processing combinatorial problems, and for establishing knowledge-based systems for the web. The conference Declare 2017 aims to promote the cross-fertilizing exchange of ideas and experiences among researches and students from the different communities interested in the foundations, applications, and combinations of high-level, declarative programming and related areas. It was be accompanied by a one-week summer school on Advanced Concepts for Databases and Logic Programming for students and PhD students.
  @techreport{seipel2017declare, abstract = {This technical report contains the papers presented at the Conference on Declarative Programming Declare 2017, in Würzburg, Germany, from September 19th to 22th, 2017. The joint conference consisted of the 21st International Conference on Applications of Declarative Programming and Knowledge Management INAP 2017, the 31st Workshop on Logic Programming WLP 2017, and the 25th Workshop on Functional and (Constraint) Logic Programming WFLP 2017. Declarative programming is an advanced paradigm for modeling and solving complex problems. This method has attracted increased attention over the last decades, e.g., in the domains of data and knowledge engineering, databases, artificial intelligence, natural language processing, modeling and processing combinatorial problems, and for establishing knowledge-based systems for the web. The conference Declare 2017 aims to promote the cross-fertilizing exchange of ideas and experiences among researches and students from the different communities interested in the foundations, applications, and combinations of high-level, declarative programming and related areas. It was be accompanied by a one-week summer school on Advanced Concepts for Databases and Logic Programming for students and PhD students.}, editor = {Seipel, Dietmar and Hanus, Michael and Abreu, Salvador}, institution = {Institut für Informatik}, month = {September}, number = 499, title = {Declare 2017 – Conference on Declarative Programming}, year = 2017 }
• Loh, F., Burger, V., Wamser, F., Tran-Gia, P., Schembra, G., Rametta, C.: Performance Evaluation of Video Streaming Service Chains in Softwarized 5G Networks with Task Graph Reduction. 29th International Teletraffic Congress (ITC) (2017).
  [ BibTeX ]
   
  @inproceedings{info3-inproceedings-2017-18, author = {Loh, Frank and Burger, Valentin and Wamser, Florian and Tran-Gia, Phuoc and Schembra, Giovanni and Rametta, Corrado}, booktitle = {29th International Teletraffic Congress (ITC)}, month = 9, title = {Performance Evaluation of Video Streaming Service Chains in Softwarized 5G Networks with Task Graph Reduction}, year = 2017 }
• Dinh-Xuan, L., Popp, C., Burger, V., Wamser, F.: Study on VNF-based QoE Monitoring in the Cloud. Special Issue of Scalable Computing and Communications Journal on Software-Defined Networking and Network Function Virtualization. (2017).
  [ Abstract ] [ BibTeX ]
   
  The fast growth of video streaming is responsible for a huge amount of traffic over the past few years. Due to the variety and popularity of video content on the Internet, a potential market is emerging for video providers, but also poses challenges for network operators in order to meet users' expectations. To address this problem, network operators need a mechanism to monitor the video quality and Quality of Experience (QoE) as perceived by the users. This allows reacting on quality degradations to improve the service in the network. With the paradigm of Network Function Virtualization, network operators are able to deploy such a Virtual Network Function (VNF) for video monitoring in the cloud. In this work, we investigate the feasibility of deploying a VNF for video buffer monitoring in the Amazon Web Service (AWS) cloud. To this end, we implement the VNF to analyze video flows in the network by using deep packet inspection. We investigate the influence of different points of presence (PoP) and a high mobility environment on the accuracy of the VNF for monitoring the video buffer and QoE perceived by the users. Our findings show that the accuracy of the VNF for video buffer monitoring decreases with the distance of the PoP to the client. This is not only due to the delay and bottleneck between the monitoring point and the client, but also due to the high mobility client access network. This means with increasing distance of the PoP to the client in a mobility environment, the probability of detecting stalling events also decreases, which is key factor to evaluate the QoE for video streaming.
  @article{info3-article-2017-7, abstract = {The fast growth of video streaming is responsible for a huge amount of traffic over the past few years. Due to the variety and popularity of video content on the Internet, a potential market is emerging for video providers, but also poses challenges for network operators in order to meet users' expectations. To address this problem, network operators need a mechanism to monitor the video quality and Quality of Experience (QoE) as perceived by the users. This allows reacting on quality degradations to improve the service in the network. With the paradigm of Network Function Virtualization, network operators are able to deploy such a Virtual Network Function (VNF) for video monitoring in the cloud. In this work, we investigate the feasibility of deploying a VNF for video buffer monitoring in the Amazon Web Service (AWS) cloud. To this end, we implement the VNF to analyze video flows in the network by using deep packet inspection. We investigate the influence of different points of presence (PoP) and a high mobility environment on the accuracy of the VNF for monitoring the video buffer and QoE perceived by the users. Our findings show that the accuracy of the VNF for video buffer monitoring decreases with the distance of the PoP to the client. This is not only due to the delay and bottleneck between the monitoring point and the client, but also due to the high mobility client access network. This means with increasing distance of the PoP to the client in a mobility environment, the probability of detecting stalling events also decreases, which is key factor to evaluate the QoE for video streaming.}, author = {Dinh-Xuan, Lam and Popp, Christian and Burger, Valentin and Wamser, Florian}, journal = {Special Issue of Scalable Computing and Communications Journal on Software-Defined Networking and Network Function Virtualization}, number = {SCAC-D-17-00027R1}, title = {Study on VNF-based QoE Monitoring in the Cloud}, year = 2017 }
• Kamneng Kwam, B.: Performance Evaluation of Placement Algorithms for Service Chains, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2017-16, author = {Kamneng Kwam, Brice}, month = 9, school = {University of Würzburg}, title = {Performance Evaluation of Placement Algorithms for Service Chains}, year = 2017 }
• Ring, M., Wunderlich, S., Grüdl, D., Landes, D., Hotho, A.: A Toolset for Intrusion and Insider Threat Detection. In: Palomares Carrascosa, I., Kalutarage, H.K., und Huang, Y. (hrsg.) Data Analytics and Decision Support for Cybersecurity: Trends, Methodologies and Applications. S. 3--31. Springer International Publishing, Cham (2017).
  [ Abstract ] [ BibTeX ] [ URL ] [ DOI ]
   
  Company data are a valuable asset and must be protected against unauthorized access and manipulation. In this contribution, we report on our ongoing work that aims to support IT security experts with identifying novel or obfuscated attacks in company networks, irrespective of their origin inside or outside the company network. A new toolset for anomaly based network intrusion detection is proposed. This toolset uses flow-based data which can be easily retrieved by central network components. We study the challenges of analysing flow-based data streams using data mining algorithms and build an appropriate approach step by step. In contrast to previous work, we collect flow-based data for each host over a certain time window, include the knowledge of domain experts and analyse the data from three different views. We argue that incorporating expert knowledge and previous flows allow us to create more meaningful attributes for subsequent analysis methods. This way, we try to detect novel attacks while simultaneously limiting the number of false positives.
  @inbook{Ring2017, abstract = {Company data are a valuable asset and must be protected against unauthorized access and manipulation. In this contribution, we report on our ongoing work that aims to support IT security experts with identifying novel or obfuscated attacks in company networks, irrespective of their origin inside or outside the company network. A new toolset for anomaly based network intrusion detection is proposed. This toolset uses flow-based data which can be easily retrieved by central network components. We study the challenges of analysing flow-based data streams using data mining algorithms and build an appropriate approach step by step. In contrast to previous work, we collect flow-based data for each host over a certain time window, include the knowledge of domain experts and analyse the data from three different views. We argue that incorporating expert knowledge and previous flows allow us to create more meaningful attributes for subsequent analysis methods. This way, we try to detect novel attacks while simultaneously limiting the number of false positives.}, address = {Cham}, author = {Ring, Markus and Wunderlich, Sarah and Grüdl, Dominik and Landes, Dieter and Hotho, Andreas}, booktitle = {Data Analytics and Decision Support for Cybersecurity: Trends, Methodologies and Applications}, editor = {Palomares Carrascosa, Iván and Kalutarage, Harsha Kumara and Huang, Yan}, pages = {3--31}, publisher = {Springer International Publishing}, title = {A Toolset for Intrusion and Insider Threat Detection}, year = 2017 }
• Tüchert, A.: Influence of loading delays on the perceived quality of web-based enterprise portals, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2017-8, author = {Tüchert, Andrea}, month = 5, school = {University of Wuerzburg}, title = {Influence of loading delays on the perceived quality of web-based enterprise portals}, year = 2017 }
• Loh, F.: Influence of Tension on QoE in Video Streaming, (2017).
  [ Abstract ] [ BibTeX ]
   
  Goal of this thesis is to write a web page for a QoE study to determine if the stalling position has an impact on the user's QoE. Additionally, the impact of seamless continuation after stalling should be compared to skipping a part of the video (for example the most exciting position)
  @mastersthesis{info3-bachelor-2017-27, abstract = {Goal of this thesis is to write a web page for a QoE study to determine if the stalling position has an impact on the user's QoE. Additionally, the impact of seamless continuation after stalling should be compared to skipping a part of the video (for example the most exciting position)}, author = {Loh, Frank}, school = {University of Würzburg}, title = {Influence of Tension on QoE in Video Streaming}, year = 2017 }
• Becker, M., Lemmerich, F., Singer, P., Strohmaier, M., Hotho, A.: MixedTrails: Bayesian hypothesis comparison on heterogeneous sequential data. Data Mining and Knowledge Discovery. (2017).
  [ Abstract ] [ BibTeX ] [ URL ] [ DOI ]
   
  Sequential traces of user data are frequently observed online and offline, e.g., as sequences of visited websites or as sequences of locations captured by GPS. However, understanding factors explaining the production of sequence data is a challenging task, especially since the data generation is often not homogeneous. For example, navigation behavior might change in different phases of browsing a website or movement behavior may vary between groups of users. In this work, we tackle this task and propose MixedTrails , a Bayesian approach for comparing the plausibility of hypotheses regarding the generative processes of heterogeneous sequence data. Each hypothesis is derived from existing literature, theory, or intuition and represents a belief about transition probabilities between a set of states that can vary between groups of observed transitions. For example, when trying to understand human movement in a city and given some data, a hypothesis assuming tourists to be more likely to move towards points of interests than locals can be shown to be more plausible than a hypothesis assuming the opposite. Our approach incorporates such hypotheses as Bayesian priors in a generative mixed transition Markov chain model, and compares their plausibility utilizing Bayes factors. We discuss analytical and approximate inference methods for calculating the marginal likelihoods for Bayes factors, give guidance on interpreting the results, and illustrate our approach with several experiments on synthetic and empirical data from Wikipedia and Flickr. Thus, this work enables a novel kind of analysis for studying sequential data in many application areas.
  @article{Becker2017, abstract = {Sequential traces of user data are frequently observed online and offline, e.g., as sequences of visited websites or as sequences of locations captured by GPS. However, understanding factors explaining the production of sequence data is a challenging task, especially since the data generation is often not homogeneous. For example, navigation behavior might change in different phases of browsing a website or movement behavior may vary between groups of users. In this work, we tackle this task and propose MixedTrails , a Bayesian approach for comparing the plausibility of hypotheses regarding the generative processes of heterogeneous sequence data. Each hypothesis is derived from existing literature, theory, or intuition and represents a belief about transition probabilities between a set of states that can vary between groups of observed transitions. For example, when trying to understand human movement in a city and given some data, a hypothesis assuming tourists to be more likely to move towards points of interests than locals can be shown to be more plausible than a hypothesis assuming the opposite. Our approach incorporates such hypotheses as Bayesian priors in a generative mixed transition Markov chain model, and compares their plausibility utilizing Bayes factors. We discuss analytical and approximate inference methods for calculating the marginal likelihoods for Bayes factors, give guidance on interpreting the results, and illustrate our approach with several experiments on synthetic and empirical data from Wikipedia and Flickr. Thus, this work enables a novel kind of analysis for studying sequential data in many application areas.}, author = {Becker, Martin and Lemmerich, Florian and Singer, Philipp and Strohmaier, Markus and Hotho, Andreas}, journal = {Data Mining and Knowledge Discovery}, month = {jul}, title = {MixedTrails: Bayesian hypothesis comparison on heterogeneous sequential data}, year = 2017 }
• Allendorf, F.: Assessing the Impact of Network Impairments on the Performance of Players in DOTA 2, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2017-11, author = {Allendorf, Fabian}, month = 3, school = {University of Würzburg}, title = {Assessing the Impact of Network Impairments on the Performance of Players in DOTA 2}, year = 2017 }
• Seufert, M.: Research Activities Report for "Crowdsourcing TF" and "Managing Web & Cloud QoE TF". , 11th Qualinet General Meeting, Erfurt, Germany (2017).
  [ BibTeX ]
   
  @presentation{info3-presentation-2017-2, address = {11th Qualinet General Meeting, Erfurt, Germany}, author = {Seufert, Michael}, month = 5, title = {Research Activities Report for "Crowdsourcing TF" and "Managing Web & Cloud QoE TF"}, year = 2017 }
• Seufert, M.: Unperturbed Video Streaming QoE Under Web Page Related Context Factors. , 9th International Conference on Quality of Multimedia Experience (QoMEX), Erfurt, Germany (2017).
  [ BibTeX ]
   
  @presentation{info3-presentation-2017-3, address = {9th International Conference on Quality of Multimedia Experience (QoMEX), Erfurt, Germany}, author = {Seufert, Michael}, month = 6, title = {Unperturbed Video Streaming QoE Under Web Page Related Context Factors}, year = 2017 }
• Beutel, A.: Integration of SDN Performance Monitoring in existing Network Management Software, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2017-12, author = {Beutel, Armin}, month = 3, school = {University of Würzburg}, title = {Integration of SDN Performance Monitoring in existing Network Management Software}, year = 2017 }
• Achenbach, J., Waltemate, T., Latoschik, M.E., Botsch, M.: Fast Generation of Realistic Virtual Humans. 23rd ACM Symposium on Virtual Reality Software and Technology (VRST) (2017).
  [ BibTeX ]
   
  @inproceedings{achenbach2017generation, author = {Achenbach, Jascha and Waltemate, Thomas and Latoschik, Marc Erich and Botsch, Mario}, booktitle = {23rd ACM Symposium on Virtual Reality Software and Technology (VRST)}, note = {Accepted, to be published}, title = {Fast Generation of Realistic Virtual Humans}, year = 2017 }
• Meixner, M.: Methods for Assessment of Multi-objective Optimization Algorithms with Application in the Context of SDN, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2017-2, author = {Meixner, Markus}, month = 7, school = {University of Würzburg}, title = {Methods for Assessment of Multi-objective Optimization Algorithms with Application in the Context of SDN}, year = 2017 }
• Supervisor: Schwind, A.: Einfluss der Virtualisierungsschicht auf das Anwendungsverhalten, (2017).
  [ Abstract ] [ BibTeX ]
   
  Contact: anika.schwind@informatik.uni-wuerzburg.de
  @mastersthesis{info3-bachelor-2017-26, abstract = {Contact: anika.schwind@informatik.uni-wuerzburg.de}, author = {Supervisor: Schwind, Anika}, school = {University of Wuerzburg}, title = {Einfluss der Virtualisierungsschicht auf das Anwendungsverhalten}, year = 2017 }
• Furth, S., Baumeister, J.: Constructing Technical Knowledge Organizations from Document Structures. In: Frasincar, F., Ittoo, A., Nguyen, L.M., und Métais, E. (hrsg.) Natural Language Processing and Information Systems: 22nd International Conference on Applications of Natural Language to Information Systems, NLDB 2017, Liège, Belgium, June 21-23, 2017, Proceedings. S. 210--213. Springer International Publishing, Cham (2017).
  [ BibTeX ] [ URL ] [ DOI ]
   
  @inproceedings{Furth2017, address = {Cham}, author = {Furth, Sebastian and Baumeister, Joachim}, booktitle = {Natural Language Processing and Information Systems: 22nd International Conference on Applications of Natural Language to Information Systems, NLDB 2017, Liège, Belgium, June 21-23, 2017, Proceedings}, editor = {Frasincar, Flavius and Ittoo, Ashwin and Nguyen, Le Minh and Métais, Elisabeth}, pages = {210--213}, publisher = {Springer International Publishing}, title = {Constructing Technical Knowledge Organizations from Document Structures}, year = 2017 }
• Scherer, K.P., Knöll, D., Baumeister, J., Furth, S.: Knowledge Acquisition by Selflearning Methods with Structured Clinical Data. IJAS: International Conference on Arts and Sciences. , Montreal (2017).
  [ BibTeX ]
   
  @inproceedings{scherer2017knowledge, address = {Montreal}, author = {Scherer, Klaus Peter and Knöll, Daniel and Baumeister, Joachim and Furth, Sebastian}, booktitle = {IJAS: International Conference on Arts and Sciences}, title = {Knowledge Acquisition by Selflearning Methods with Structured Clinical Data}, year = 2017 }
• Lange, S., Grigorjew, A., Zinner, T., Tran-Gia, P., Jarschel, M.: A Multi-Objective Heuristic for the Optimization of Virtual Network Function Chain Placement. 29th International Teletraffic Congress (ITC) (2017).
  [ BibTeX ]
   
  @inproceedings{info3-inproceedings-2017-16, author = {Lange, Stanislav and Grigorjew, Alexej and Zinner, Thomas and Tran-Gia, Phuoc and Jarschel, Michael}, booktitle = {29th International Teletraffic Congress (ITC)}, month = 9, title = {A Multi-Objective Heuristic for the Optimization of Virtual Network Function Chain Placement}, year = 2017 }
• Niebling, F.: Spatial Interaction for the Post-Processing of 3D CFD Datasets. In: Kozlikova, B., Schreck, T., und Wischgoll, T. (hrsg.) EuroVis 2017 - Short Papers. The Eurographics Association (2017).
  [ BibTeX ] [ DOI ]
   
  @inproceedings{eurovisshort.20171136, author = {Niebling, Florian}, booktitle = {EuroVis 2017 - Short Papers}, editor = {Kozlikova, Barbora and Schreck, Tobias and Wischgoll, Thomas}, publisher = {The Eurographics Association}, title = {Spatial Interaction for the Post-Processing of 3D CFD Datasets}, year = 2017 }
• Seufert, M., Lange, S., Meixner, M.: Automated Decision Making based on Pareto Frontiers in the Context of Service Placement in Networks. 29th International Teletraffic Congress (ITC) (2017).
  [ Abstract ] [ BibTeX ]
   
  Virtualization paradigms like cloud computing, software defined networking (SDN), and network functions virtualization (NFV) provide advantages with respect to aspects like flexibility, costs, and scalability. However, management and orchestration of the resulting networks also introduce new challenges. The placement of services, such as virtual machines~(VMs), virtualized network functions~(VNFs), or SDN controllers, is a multi-objective optimization task that confronts operators with a multitude of possible solutions that are incomparable among each other. The goal of this work is to investigate mechanisms that enable automated decision making between such multi-dimensional solutions. To this end, we investigate techniques from the domain of multi-attribute decision making that aggregate the performance of placements to a single numeric score. A comparison between resulting rankings of placements shows that many techniques produce similar results. Hence, placements that achieve good rankings according to many approaches might be viable candidates in the context of automated decision making. In order to illustrate the functionality of the different scoring mechanisms, we perform a case study on a single network graph and a fixed number of objectives and service instances. Additionally, we present aggregated results from broad evaluations on the Internet Topology Zoo and a larger number of objectives as well as varying numbers of service instances. These allow making more reliable statements about the mechanisms' performance and agreement.
  @inproceedings{info3-article-2017-6, abstract = {Virtualization paradigms like cloud computing, software defined networking (SDN), and network functions virtualization (NFV) provide advantages with respect to aspects like flexibility, costs, and scalability. However, management and orchestration of the resulting networks also introduce new challenges. The placement of services, such as virtual machines~(VMs), virtualized network functions~(VNFs), or SDN controllers, is a multi-objective optimization task that confronts operators with a multitude of possible solutions that are incomparable among each other. The goal of this work is to investigate mechanisms that enable automated decision making between such multi-dimensional solutions. To this end, we investigate techniques from the domain of multi-attribute decision making that aggregate the performance of placements to a single numeric score. A comparison between resulting rankings of placements shows that many techniques produce similar results. Hence, placements that achieve good rankings according to many approaches might be viable candidates in the context of automated decision making. In order to illustrate the functionality of the different scoring mechanisms, we perform a case study on a single network graph and a fixed number of objectives and service instances. Additionally, we present aggregated results from broad evaluations on the Internet Topology Zoo and a larger number of objectives as well as varying numbers of service instances. These allow making more reliable statements about the mechanisms' performance and agreement.}, author = {Seufert, Michael and Lange, Stanislav and Meixner, Markus}, booktitle = {29th International Teletraffic Congress (ITC)}, month = 9, title = {Automated Decision Making based on Pareto Frontiers in the Context of Service Placement in Networks}, year = 2017 }
• Singer, P., Helic, D., Hotho, A., Strohmaier, M.: A Bayesian Method for Comparing Hypotheses About Human Trails. ACM Trans. Web. 11, 14:1--14:29 (2017).
  [ Abstract ] [ BibTeX ] [ URL ] [ DOI ]
   
  When users interact with the Web today, they leave sequential digital trails on a massive scale. Examples of such human trails include Web navigation, sequences of online restaurant reviews, or online music play lists. Understanding the factors that drive the production of these trails can be useful, for example, for improving underlying network structures, predicting user clicks, or enhancing recommendations. In this work, we present a method called HypTrails for comparing a set of hypotheses about human trails on the Web, where hypotheses represent beliefs about transitions between states. Our method utilizes Markov chain models with Bayesian inference. The main idea is to incorporate hypotheses as informative Dirichlet priors and to calculate the evidence of the data under them. For eliciting Dirichlet priors from hypotheses, we present an adaption of the so-called (trial) roulette method, and to compare the relative plausibility of hypotheses, we employ Bayes factors. We demonstrate the general mechanics and applicability of HypTrails by performing experiments with (i) synthetic trails for which we control the mechanisms that have produced them and (ii) empirical trails stemming from different domains including Web site navigation, business reviews, and online music played. Our work expands the repertoire of methods available for studying human trails.
  @article{singer2017bayesian, abstract = {When users interact with the Web today, they leave sequential digital trails on a massive scale. Examples of such human trails include Web navigation, sequences of online restaurant reviews, or online music play lists. Understanding the factors that drive the production of these trails can be useful, for example, for improving underlying network structures, predicting user clicks, or enhancing recommendations. In this work, we present a method called HypTrails for comparing a set of hypotheses about human trails on the Web, where hypotheses represent beliefs about transitions between states. Our method utilizes Markov chain models with Bayesian inference. The main idea is to incorporate hypotheses as informative Dirichlet priors and to calculate the evidence of the data under them. For eliciting Dirichlet priors from hypotheses, we present an adaption of the so-called (trial) roulette method, and to compare the relative plausibility of hypotheses, we employ Bayes factors. We demonstrate the general mechanics and applicability of HypTrails by performing experiments with (i) synthetic trails for which we control the mechanisms that have produced them and (ii) empirical trails stemming from different domains including Web site navigation, business reviews, and online music played. Our work expands the repertoire of methods available for studying human trails.}, address = {New York, NY, USA}, author = {Singer, Philipp and Helic, Denis and Hotho, Andreas and Strohmaier, Markus}, journal = {ACM Trans. Web}, month = {jun}, number = 3, pages = {14:1--14:29}, publisher = {ACM}, title = {A Bayesian Method for Comparing Hypotheses About Human Trails}, volume = 11, year = 2017 }
• Chaplick, S., Fleszar, K., Lipp, F., Ravsky, A., Verbitsky, O., Wolff, A.: The Complexity of Drawing Graphs on Few Lines and Few Planes. In: Ellen, F., Kolokolova, A., und Sack, J.-R. (hrsg.) Proc. Algorithms Data Struct. Symp. (WADS'17). S. 265--276. Springer-Verlag (2017).
  [ Abstract ] [ BibTeX ] [ URL ] [ DOI ]
   
  It is well known that any graph admits a crossing-free straight-line drawing in  \\($\$\)backslashmathbb R ^3\\($\$\) and that any planar graph admits the same even in  \\($\$\)backslashmathbb R ^2\\($\$\) . For a graph G and \\($\$\)d backslashin \backslash\2,3\backslash\\\($\$\) , let \\($\$\)backslashrho ^1\_d(G)\\($\$\) denote the minimum number of lines in \\($\$\)backslashmathbb R ^d\\($\$\) that together can cover all edges of a drawing of G. For \\($\$\)d=2\\($\$\) , G must be planar. We investigate the complexity of computing these parameters and obtain the following hardness and algorithmic results.
  @inbook{cflrvw-cdgfl-WADS17, abstract = {It is well known that any graph admits a crossing-free straight-line drawing in  \\($\$\)backslashmathbb R ^3\\($\$\) and that any planar graph admits the same even in  \\($\$\)backslashmathbb R ^2\\($\$\) . For a graph G and \\($\$\)d backslashin \backslash\2,3\backslash\\\($\$\) , let \\($\$\)backslashrho ^1\_d(G)\\($\$\) denote the minimum number of lines in \\($\$\)backslashmathbb R ^d\\($\$\) that together can cover all edges of a drawing of G. For \\($\$\)d=2\\($\$\) , G must be planar. We investigate the complexity of computing these parameters and obtain the following hardness and algorithmic results.}, author = {Chaplick, Steven and Fleszar, Krzysztof and Lipp, Fabian and Ravsky, Alexander and Verbitsky, Oleg and Wolff, Alexander}, booktitle = {Proc. Algorithms Data Struct. Symp. (WADS'17)}, editor = {Ellen, Faith and Kolokolova, Antonina and Sack, Jörg-Rüdiger}, pages = {265--276}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {The Complexity of Drawing Graphs on Few Lines and Few Planes}, volume = 10389, year = 2017 }
• Furth, S., Schirm, M., Belli, V., Baumeister, J.: TEKNO: Preparing Legacy Technical Documents for Semantic Information Systems. In: Frasincar, F., Ittoo, A., Nguyen, L.M., und Métais, E. (hrsg.) Natural Language Processing and Information Systems: 22nd International Conference on Applications of Natural Language to Information Systems, NLDB 2017, Liège, Belgium, June 21-23, 2017, Proceedings. S. 429--434. Springer International Publishing, Cham (2017).
  [ BibTeX ] [ URL ] [ DOI ]
   
  @inproceedings{Furth2017, address = {Cham}, author = {Furth, Sebastian and Schirm, Maximilian and Belli, Volker and Baumeister, Joachim}, booktitle = {Natural Language Processing and Information Systems: 22nd International Conference on Applications of Natural Language to Information Systems, NLDB 2017, Liège, Belgium, June 21-23, 2017, Proceedings}, editor = {Frasincar, Flavius and Ittoo, Ashwin and Nguyen, Le Minh and Métais, Elisabeth}, pages = {429--434}, publisher = {Springer International Publishing}, title = {TEKNO: Preparing Legacy Technical Documents for Semantic Information Systems}, year = 2017 }
• Supervisor: Dinh-Xuan, L.: Implementing (QoE) monitoring services at Amazon AWS Cloud Service, (2017).
  [ Abstract ] [ BibTeX ]
   
  Monitoring the Quality of Experience (QoE) perceived by the end users can be done by implementing a Virtual Network Function (VNF) on the cloud. This helps providers to be aware of the QoE level for a dedicated service at the client side. The output of the function can be used for service management which aims to improve the service if the users experience a low service quality.
  @mastersthesis{info3-bachelor-2017-9, abstract = {Monitoring the Quality of Experience (QoE) perceived by the end users can be done by implementing a Virtual Network Function (VNF) on the cloud. This helps providers to be aware of the QoE level for a dedicated service at the client side. The output of the function can be used for service management which aims to improve the service if the users experience a low service quality.}, author = {Supervisor: Dinh-Xuan, Lam}, school = {University of Würzburg}, title = {Implementing (QoE) monitoring services at Amazon AWS Cloud Service}, year = 2017 }
• Maiwald, F., Vietze, T., Schneider, D., Münster, S., Niebling, F.: Photogrammetric Analysis of Historical Image Repositories for Virtual Reconstruction in the Field of Digital Humanities. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. XLII-2/W3, 447-452 (2017).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  Historical photographs contain high density of information and are of great importance as sources in humanities research. In addition to the semantic indexing of historical images based on metadata, it is also possible to reconstruct geometric information about the depicted objects or the camera position at the time of the recording by employing photogrammetric methods. The approach presented here is intended to investigate (semi-) automated photogrammetric reconstruction methods for heterogeneous collections of historical (city) photographs and photographic documentation for the use in the humanities, urban research and history sciences. From a photogrammetric point of view, these images are mostly digitized photographs. For a photogrammetric evaluation, therefore, the characteristics of scanned analog images with mostly unknown camera geometry, missing or minimal object information and low radiometric and geometric resolution have to be considered. In addition, these photographs have not been created specifically for documentation purposes and so the focus of these images is often not on the object to be evaluated. The image repositories must therefore be subjected to a preprocessing analysis of their photogrammetric usability. Investigations are carried out on the basis of a repository containing historical images of the Kronentor ("crown gate") of the Dresden Zwinger. The initial step was to assess the quality and condition of available images determining their appropriateness for generating three-dimensional point clouds from historical photos using a structure-from-motion evaluation (SfM). Then, the generated point clouds were assessed by comparing them with current measurement data of the same object.
  @article{noauthororeditor2017photogrammetric, abstract = {Historical photographs contain high density of information and are of great importance as sources in humanities research. In addition to the semantic indexing of historical images based on metadata, it is also possible to reconstruct geometric information about the depicted objects or the camera position at the time of the recording by employing photogrammetric methods. The approach presented here is intended to investigate (semi-) automated photogrammetric reconstruction methods for heterogeneous collections of historical (city) photographs and photographic documentation for the use in the humanities, urban research and history sciences. From a photogrammetric point of view, these images are mostly digitized photographs. For a photogrammetric evaluation, therefore, the characteristics of scanned analog images with mostly unknown camera geometry, missing or minimal object information and low radiometric and geometric resolution have to be considered. In addition, these photographs have not been created specifically for documentation purposes and so the focus of these images is often not on the object to be evaluated. The image repositories must therefore be subjected to a preprocessing analysis of their photogrammetric usability. Investigations are carried out on the basis of a repository containing historical images of the Kronentor ("crown gate") of the Dresden Zwinger. The initial step was to assess the quality and condition of available images determining their appropriateness for generating three-dimensional point clouds from historical photos using a structure-from-motion evaluation (SfM). Then, the generated point clouds were assessed by comparing them with current measurement data of the same object.}, author = {Maiwald, Ferdinand and Vietze, Theresa and Schneider, Danilo and Münster, Sander and Niebling, Florian}, journal = {ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences}, month = {feb}, pages = {447-452}, title = {Photogrammetric Analysis of Historical Image Repositories for Virtual Reconstruction in the Field of Digital Humanities}, volume = {XLII-2/W3}, year = 2017 }
• Latoschik, M.E., Roth, D., Gall, D., Achenbach, J., Waltemate, T., Botsch, M.: The Effect of Avatar Realism in Immersive Social Virtual Realities. 23rd ACM Symposium on Virtual Reality Software and Technology (VRST 2017) (2017).
  [ BibTeX ]
   
  @inproceedings{latoschik2017effect, author = {Latoschik, Marc Erich and Roth, Daniel and Gall, Dominik and Achenbach, Jascha and Waltemate, Thomas and Botsch, Mario}, booktitle = {23rd ACM Symposium on Virtual Reality Software and Technology (VRST 2017)}, note = {Accepted, to be published}, title = {The Effect of Avatar Realism in Immersive Social Virtual Realities}, year = 2017 }
• Fischbach, M.: Enhancing Software Quality of Multimodal Interactive Systems, https://opus.bibliothek.uni-wuerzburg.de/frontdoor/index/index/docId/15272, (2017).
  [ Abstract ] [ BibTeX ] [ URL ] [ DOI ]
   
  Multimodal interfaces (MMIs) are a promising human-computer interaction paradigm. They are feasible for a wide rang of environments, yet they are especially suited if interactions are spatially and temporally grounded with an environment in which the user is (physically) situated. Real-time interactive systems (RISs) are technical realizations for situated interaction environments, originating from application areas like virtual reality, mixed reality, human-robot interaction, and computer games. RISs include various dedicated processing-, simulation-, and rendering subsystems which collectively maintain a real-time simulation of a coherent application state. They thus fulfil the complex functional requirements of their application areas. Two contradicting principles determine the architecture of RISs: coupling and cohesion. On the one hand, RIS subsystems commonly use specific data structures for multiple purposes to guarantee performance and rely on close semantic and temporal coupling between each other to maintain consistency. This coupling is exacerbated if the integration of artificial intelligence (AI) methods is necessary, such as for realizing MMIs. On the other hand, software qualities like reusability and modifiability call for a decoupling of subsystems and architectural elements with single well-defined purposes, i.e., high cohesion. Systems predominantly favour performance and consistency over reusability and modifiability to handle this contradiction. They thus accept low maintainability in general and hindered scientific progress in the long-term. This thesis presents six semantics-based techniques that extend the established entity-component system (ECS) pattern and pose a solution to this contradiction without sacrificing maintainability: semantic grounding, a semantic entity-component state, grounded actions, semantic queries, code from semantics, and decoupling by semantics. The extension solves the ECS pattern's runtime type deficit, improves component granularity, facilitates access to entity properties outside a subsystem's component association, incorporates a concept to semantically describe behavior as complement to the state representation, and enables compatibility even between RISs. The presented reference implementation Simulator X validates the feasibility of the six techniques and may be (re)used by other researchers due to its availability under an open-source licence. It includes a repertoire of common multimodal input processing steps that showcase the particular adequacy of the six techniques for such processing. The repertoire adds up to the integrated multimodal processing framework miPro, making Simulator X a RIS platform with explicit MMI support. The six semantics-based techniques as well as the reference implementation are validated by four expert reviews, multiple proof of concept prototypes, and two explorative studies. Informal insights gathered throughout the design and development supplement this assessment in the form of lessons learned meant to aid future development in the area.
  @phdthesis{fischbach2017enhancing, abstract = {Multimodal interfaces (MMIs) are a promising human-computer interaction paradigm. They are feasible for a wide rang of environments, yet they are especially suited if interactions are spatially and temporally grounded with an environment in which the user is (physically) situated. Real-time interactive systems (RISs) are technical realizations for situated interaction environments, originating from application areas like virtual reality, mixed reality, human-robot interaction, and computer games. RISs include various dedicated processing-, simulation-, and rendering subsystems which collectively maintain a real-time simulation of a coherent application state. They thus fulfil the complex functional requirements of their application areas. Two contradicting principles determine the architecture of RISs: coupling and cohesion. On the one hand, RIS subsystems commonly use specific data structures for multiple purposes to guarantee performance and rely on close semantic and temporal coupling between each other to maintain consistency. This coupling is exacerbated if the integration of artificial intelligence (AI) methods is necessary, such as for realizing MMIs. On the other hand, software qualities like reusability and modifiability call for a decoupling of subsystems and architectural elements with single well-defined purposes, i.e., high cohesion. Systems predominantly favour performance and consistency over reusability and modifiability to handle this contradiction. They thus accept low maintainability in general and hindered scientific progress in the long-term. This thesis presents six semantics-based techniques that extend the established entity-component system (ECS) pattern and pose a solution to this contradiction without sacrificing maintainability: semantic grounding, a semantic entity-component state, grounded actions, semantic queries, code from semantics, and decoupling by semantics. The extension solves the ECS pattern's runtime type deficit, improves component granularity, facilitates access to entity properties outside a subsystem's component association, incorporates a concept to semantically describe behavior as complement to the state representation, and enables compatibility even between RISs. The presented reference implementation Simulator X validates the feasibility of the six techniques and may be (re)used by other researchers due to its availability under an open-source licence. It includes a repertoire of common multimodal input processing steps that showcase the particular adequacy of the six techniques for such processing. The repertoire adds up to the integrated multimodal processing framework miPro, making Simulator X a RIS platform with explicit MMI support. The six semantics-based techniques as well as the reference implementation are validated by four expert reviews, multiple proof of concept prototypes, and two explorative studies. Informal insights gathered throughout the design and development supplement this assessment in the form of lessons learned meant to aid future development in the area.}, author = {Fischbach, Martin}, publisher = {Universität Würzburg}, title = {Enhancing Software Quality of Multimodal Interactive Systems}, type = {Doctoral Thesis}, year = 2017 }
• Waigand, M.: Towards Traffic Management for Mobile Group-based Communication in WhatsApp, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2017-19, author = {Waigand, Marco}, month = 8, school = {University of Würzburg}, title = {Towards Traffic Management for Mobile Group-based Communication in WhatsApp}, year = 2017 }
• Supervisor: Metter, C.: Towards OFCProbe 2.0, (2017).
  [ Abstract ] [ BibTeX ]
   
  OFCProbe is a tool to evaluate the performance and behaviour of SDN controllers. Virtual switches generate requests and measure the responses. Today some parts of OFCProbe are outdated. The task is to implement a new version of OFCProbe supporting some of the lastest SDN protocols whilst migrating the architecture of the tool to a more distributed approach, e.g. by using message brokers like ActiveMQ and/or in-memory data grids like Hazelcast. <christopher.metter@informatik.uni-wuerzburg.de>
  @mastersthesis{info3-master-2017-2, abstract = {OFCProbe is a tool to evaluate the performance and behaviour of SDN controllers. Virtual switches generate requests and measure the responses. Today some parts of OFCProbe are outdated. The task is to implement a new version of OFCProbe supporting some of the lastest SDN protocols whilst migrating the architecture of the tool to a more distributed approach, e.g. by using message brokers like ActiveMQ and/or in-memory data grids like Hazelcast. <christopher.metter@informatik.uni-wuerzburg.de>}, author = {Supervisor: Metter, Christopher}, school = {University of Würzburg}, title = {Towards OFCProbe 2.0}, year = 2017 }
• Metter, C., Seufert, M., Wamser, F., Zinner, T., Tran-Gia, P.: Analytical Model for SDN Signaling Traffic and Flow Table Occupancy and its Application for Various Types of Traffic. IEEE Transactions on Network and Service Management. 14, 603-615 (2017).
  [ Abstract ] [ BibTeX ]
   
  Software Defined Networking (SDN) has emerged as a promising networking paradigm overcoming various drawbacks of current communication networks. The control and data plane of switching devices is decoupled and control functions are centralized at the network controller. In SDN, each new flow introduces additional signaling traffic between the switch and the controller. Based on this traffic, rules are created in the flow table of the switch, which specify the forwarding behavior. To avoid table overflows, unused entries are removed after a predefined time-out period. Given a specific traffic mix, the choice of this time-out period affects the trade-off between signaling rate and table occupancy. As a result, network operators have to adjust this parameter to enable a smooth and efficient network operation. Due to the complexity of this problem caused by the various traffic flows in a network, a suitable abstraction is necessary in order to derive valid parameter values in time. The contribution of this work is threefold. Firstly, we formulate a simple analytical model that allows optimizing the network performance with respect to the table occupancy and the signaling rate. Secondly, we validate the model by means of simulation. Thirdly, we illustrate the impact of the time-out period on the signaling traffic and the flow table occupancy for different data-plane traffic mixes and characteristics. This includes scenarios with single application instances, as well as multiple application instances of different application types in an SDN-enabled network.
  @article{info3-article-2017-5, abstract = {Software Defined Networking (SDN) has emerged as a promising networking paradigm overcoming various drawbacks of current communication networks. The control and data plane of switching devices is decoupled and control functions are centralized at the network controller. In SDN, each new flow introduces additional signaling traffic between the switch and the controller. Based on this traffic, rules are created in the flow table of the switch, which specify the forwarding behavior. To avoid table overflows, unused entries are removed after a predefined time-out period. Given a specific traffic mix, the choice of this time-out period affects the trade-off between signaling rate and table occupancy. As a result, network operators have to adjust this parameter to enable a smooth and efficient network operation. Due to the complexity of this problem caused by the various traffic flows in a network, a suitable abstraction is necessary in order to derive valid parameter values in time. The contribution of this work is threefold. Firstly, we formulate a simple analytical model that allows optimizing the network performance with respect to the table occupancy and the signaling rate. Secondly, we validate the model by means of simulation. Thirdly, we illustrate the impact of the time-out period on the signaling traffic and the flow table occupancy for different data-plane traffic mixes and characteristics. This includes scenarios with single application instances, as well as multiple application instances of different application types in an SDN-enabled network.}, author = {Metter, Christopher and Seufert, Michael and Wamser, Florian and Zinner, Thomas and Tran-Gia, Phuoc}, journal = {IEEE Transactions on Network and Service Management}, month = 9, number = 3, pages = {603-615}, title = {Analytical Model for SDN Signaling Traffic and Flow Table Occupancy and its Application for Various Types of Traffic}, volume = 14, year = 2017 }
• Hotho, A., Jaeschke, R., Lerman, K.: Mining social semantics on the social web. Semantic Web. 8, 623--624 (2017).
  [ BibTeX ] [ URL ]
   
  @article{wrro115871, author = {Hotho, A. and Jaeschke, R. and Lerman, K.}, journal = {Semantic Web}, month = {April}, note = {copyright 2017 IOS Press and the authors. This is an author produced version of a paper subsequently published in Semantic Web. Uploaded in accordance with the publisher's self-archiving policy.}, number = 5, pages = {623--624}, publisher = {IOS Press}, title = {Mining social semantics on the social web}, volume = 8, year = 2017 }
• Gray, N., Zinner, T., Tran-Gia, P.: Enhancing SDN Security by Device Fingerprinting, (2017).
  [ Abstract ] [ BibTeX ]
   
  Software-defined Networking (SDN) provides an increased flexibility and cost savings by separating the data from the control plane. Despite these benefits, this separation also results in a greater attack surface as new devices and protocols are deployed. OpenFlow is one of these protocols and enables the communication between the switch and the controller. Ideally this connection takes place over an encrypted TLS channel, but as this feature is marked optional, it is not supported by all devices. This allows an attacker to eavesdrop and alter the communication, hence resulting in a comprised network. In this work, we demonstrate a new approach for authentication based on device fingerprinting to enhance the security in scenarios, where cryptographic mechanisms are unavailable.
  @misc{info3-demo-2017-2, abstract = {Software-defined Networking (SDN) provides an increased flexibility and cost savings by separating the data from the control plane. Despite these benefits, this separation also results in a greater attack surface as new devices and protocols are deployed. OpenFlow is one of these protocols and enables the communication between the switch and the controller. Ideally this connection takes place over an encrypted TLS channel, but as this feature is marked optional, it is not supported by all devices. This allows an attacker to eavesdrop and alter the communication, hence resulting in a comprised network. In this work, we demonstrate a new approach for authentication based on device fingerprinting to enhance the security in scenarios, where cryptographic mechanisms are unavailable.}, author = {Gray, Nicholas and Zinner, Thomas and Tran-Gia, Phuoc}, booktitle = {15th IFIP/IEEE International Symposium on Integrated Network Management (IM), Lisbon, Portugal, May 2017}, month = 5, title = {Enhancing SDN Security by Device Fingerprinting}, year = 2017 }
• Schwarzmann, S., Zinner, T., Dobrijevic, O.: Quantitative Comparison of Application-Network Interaction: A Case Study of Adaptive Video Streaming. Springer Quality and User Experience. (2017).
  [ Abstract ] [ BibTeX ]
   
  Managing quality of experience (QoE) is now widely accepted as a critical objective for multimedia applications and the supporting communication systems. In general, QoE management encompasses: (i) monitoring of the key influence factors and QoE indicators, and (ii) deciding on the appropriate control actions as specified by the management goal. Many multimedia applications, e.g. video streaming and audio conferencing, are able to adjust their operational parameters so as to react to variations in the network performance. However, such an adaptation feature is mostly based on a local client view of the network conditions, which may lead to an unfair allocation of network resources among heterogeneous clients and, thus, an unfair QoE distribution. In order to tackle this issue, there is the call for a cooperation between the applications and the underlying network, which includes application-network interaction (App-Net) in terms of: (1) exchanging information on the monitored QoE indicators, and (2) coordinating the QoE control actions. Various App-Net mechanisms focusing on specific use cases and applications have been proposed to date. This paper gives an overview of App-Net mechanisms and proposes a generic App-Net model that provides the means to realize a coordinated QoE-centric management. Based on the App-Net model, we develop an evaluation methodology to compare three App-Net mechanisms for managing QoE of HTTP adaptive streaming (HAS) against a baseline HAS service. The aim of this quantitative comparison is to explore the trade-offs between QoE gains and the complexity of App-Net implementation, with respect to the number of monitoring and control messages, achieved video quality, and QoE fairness among heterogeneous clients. Our ultimate goal is to set up reproducible experiments that facilitate a holistic evaluation of different App-Net mechanisms.
  @article{info3-article-2017-4, abstract = {Managing quality of experience (QoE) is now widely accepted as a critical objective for multimedia applications and the supporting communication systems. In general, QoE management encompasses: (i) monitoring of the key influence factors and QoE indicators, and (ii) deciding on the appropriate control actions as specified by the management goal. Many multimedia applications, e.g. video streaming and audio conferencing, are able to adjust their operational parameters so as to react to variations in the network performance. However, such an adaptation feature is mostly based on a local client view of the network conditions, which may lead to an unfair allocation of network resources among heterogeneous clients and, thus, an unfair QoE distribution. In order to tackle this issue, there is the call for a cooperation between the applications and the underlying network, which includes application-network interaction (App-Net) in terms of: (1) exchanging information on the monitored QoE indicators, and (2) coordinating the QoE control actions. Various App-Net mechanisms focusing on specific use cases and applications have been proposed to date. This paper gives an overview of App-Net mechanisms and proposes a generic App-Net model that provides the means to realize a coordinated QoE-centric management. Based on the App-Net model, we develop an evaluation methodology to compare three App-Net mechanisms for managing QoE of HTTP adaptive streaming (HAS) against a baseline HAS service. The aim of this quantitative comparison is to explore the trade-offs between QoE gains and the complexity of App-Net implementation, with respect to the number of monitoring and control messages, achieved video quality, and QoE fairness among heterogeneous clients. Our ultimate goal is to set up reproducible experiments that facilitate a holistic evaluation of different App-Net mechanisms.}, author = {Schwarzmann, Susanna and Zinner, Thomas and Dobrijevic, Ognjen}, journal = {Springer Quality and User Experience}, title = {Quantitative Comparison of Application-Network Interaction: A Case Study of Adaptive Video Streaming}, year = 2017 }
• Schwind, A.: Concept and Implementation of QoE Measurements in a Mobile Broadband Testbed, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2017-1, author = {Schwind, Anika}, month = 3, school = {University of Würzburg}, title = {Concept and Implementation of QoE Measurements in a Mobile Broadband Testbed}, year = 2017 }
• Abd El Hai, S.: Measuring the Applicability of the Analytic Model for SDN Controller Traffic and Switch Table Occupancy, (2017).
  [ Abstract ] [ BibTeX ]
   
  In the paper 'Analytic Model for SDN Controller Traffic and Switch Table Occupancy' a model has been created and later been verified by simulation. The next step is to test the applicability of the model by measurements. The task is to create a testbed and methods to accomplish this. <christopher.metter@informatik.uni-wuerzburg.de>
  @mastersthesis{info3-bachelor-2017-5, abstract = {In the paper 'Analytic Model for SDN Controller Traffic and Switch Table Occupancy' a model has been created and later been verified by simulation. The next step is to test the applicability of the model by measurements. The task is to create a testbed and methods to accomplish this. <christopher.metter@informatik.uni-wuerzburg.de>}, author = {Abd El Hai, Sami}, school = {University of Würzburg}, title = {Measuring the Applicability of the Analytic Model for SDN Controller Traffic and Switch Table Occupancy}, year = 2017 }
• Fischbach, M., Wiebusch, D., Latoschik, M.E.: Semantic Entity-Component State Management Techniques to Enhance Software Quality for Multimodal VR-Systems. IEEE Transactions on Visualization and Computer Graphics. 23, 1342-1351 (2017).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  Modularity, modifiability, reusability, and API usability are important qualities that determine the maintainability of complex software architectures typical for Virtual, Augmented, and Mixed Reality (VR, AR, MR) applications. These architectures address various input-, output-, and processing aspects, which are usually implemented by dedicated software modules. Collectively, these modules have to maintain the real-time simulation of a coherent application state. This requirement, however, implicates multiple semantic as well as temporal state representation- and access interdependencies between modules, exacerbating maintainable solutions. This paper presents five semantics-based software techniques for state management that extend the well-established entity-component system (ECS) pattern, foster modularity and enhance overall maintainability. A walk-through of typical implementation aspects of multimodal (speech and gesture) interfaces is used to highlight the techniques' benefits, providing a typical example for demanding software architectures in VR, AR and MR. Finally, central implementation details are compared against prominent alternatives.
  @article{fischbach2017semantic, abstract = {Modularity, modifiability, reusability, and API usability are important qualities that determine the maintainability of complex software architectures typical for Virtual, Augmented, and Mixed Reality (VR, AR, MR) applications. These architectures address various input-, output-, and processing aspects, which are usually implemented by dedicated software modules. Collectively, these modules have to maintain the real-time simulation of a coherent application state. This requirement, however, implicates multiple semantic as well as temporal state representation- and access interdependencies between modules, exacerbating maintainable solutions. This paper presents five semantics-based software techniques for state management that extend the well-established entity-component system (ECS) pattern, foster modularity and enhance overall maintainability. A walk-through of typical implementation aspects of multimodal (speech and gesture) interfaces is used to highlight the techniques' benefits, providing a typical example for demanding software architectures in VR, AR and MR. Finally, central implementation details are compared against prominent alternatives.}, author = {Fischbach, Martin and Wiebusch, Dennis and Latoschik, Marc Erich}, journal = {IEEE Transactions on Visualization and Computer Graphics}, month = {April}, note = {DOI: 10.1109/TVCG.2017.2657098}, number = 4, pages = {1342-1351}, publisher = {IEEE}, title = {Semantic Entity-Component State Management Techniques to Enhance Software Quality for Multimodal VR-Systems}, volume = 23, year = 2017 }
• Popp, C.: Study on the Accuracy of Video Monitoring VNF in High Mobility Environments, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2017-4, author = {Popp, Christian}, month = 1, school = {University of Würzburg}, title = {Study on the Accuracy of Video Monitoring VNF in High Mobility Environments}, year = 2017 }
• Loreto, V., Haklay, M., Hotho, A., Servedio, V.C.P., Stumme, G., Theunis, J., Tria, F. hrsg: Participatory sensing, opinions and collective awareness. Springer (2017).
  [ BibTeX ]
   
  @book{loreto2017participatory, editor = {Loreto, Vittorio and Haklay, Mordechai and Hotho, Andreas and Servedio, Vito C. P. and Stumme, Gerd and Theunis, Jan and Tria, Francesca}, publisher = {Springer}, title = {Participatory sensing, opinions and collective awareness}, year = 2017 }
• Kamneng Kwam, B.: Static Placement of Services on Edge Servers, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-praktikum-2017-1, author = {Kamneng Kwam, Brice}, month = 1, school = {University of Würzburg}, title = {Static Placement of Services on Edge Servers}, year = 2017 }
• Smietanka, O.: Detecting People Flows with Distributed Loudness Sensors, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2017-22, author = {Smietanka, Oskar}, month = 4, school = {University of Würzburg}, title = {Detecting People Flows with Distributed Loudness Sensors}, year = 2017 }
• Knapp, T.: Extending the Monitoring Features of ONOS, (2017).
  [ Abstract ] [ BibTeX ]
   
  The SDN controller ONOS lacks certain network monitoring capabilities. The task is to develop an ONOS application which utilizes the interfaces provided by ONOS and enableds the active measurement of a predefined set of network metrics.
  @mastersthesis{info3-praktikum-2017-2, abstract = {The SDN controller ONOS lacks certain network monitoring capabilities. The task is to develop an ONOS application which utilizes the interfaces provided by ONOS and enableds the active measurement of a predefined set of network metrics.}, author = {Knapp, Tobias}, school = {University of Würzburg}, title = {Extending the Monitoring Features of ONOS}, year = 2017 }
• Pfaffenberger, F.: Evaluation of Network Monitoring Approaches in Cloud Environments - Experiment and Testbed Design, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2017-14, author = {Pfaffenberger, Florian}, month = 6, school = {University of Wuerzburg}, title = {Evaluation of Network Monitoring Approaches in Cloud Environments - Experiment and Testbed Design}, year = 2017 }
• Supervisor: Wamser, F.: Aufbau eines Testbeds zur Demonstration von dynamischen Diensten in der Cloud, (2017).
  [ Abstract ] [ BibTeX ]
   
  Cloud Service Placement for Live Video Streaming with a Remote-Controlled Drone florian.wamser@informatik.uni-wuerzburg.de
  @mastersthesis{info3-praktikum-2017-3, abstract = {Cloud Service Placement for Live Video Streaming with a Remote-Controlled Drone florian.wamser@informatik.uni-wuerzburg.de}, author = {Supervisor: Wamser, Florian}, school = {University of Würzburg}, title = {Aufbau eines Testbeds zur Demonstration von dynamischen Diensten in der Cloud}, year = 2017 }
• Flaig, N.: Simulative Performance Comparison of Adaptation Logics for HTTP Adaptive Streaming, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2017-3, author = {Flaig, Nico}, month = 3, school = {University of Würzburg}, title = {Simulative Performance Comparison of Adaptation Logics for HTTP Adaptive Streaming}, year = 2017 }
• Bauer, A.: Impact of Game Mods on Game Sales and Player Behavior, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2017-25, author = {Bauer, André}, month = 5, school = {University of Würzburg}, title = {Impact of Game Mods on Game Sales and Player Behavior}, year = 2017 }
• Supervisor: Geissler, S.: Investigating the Feasibility of Machine Learning for Placement Problems in Softwarized Networks, (2017).
  [ Abstract ] [ BibTeX ]
   
  Softwarization is a crucial part of modern and next generation networks, increasing flexibility, scalability and efficiency. However, new challenges regarding the placement of entities like SDN controllers or virtual network functions need to be addressed in order to reap those benefits. Unfortunately, most of these problems are NP-hard and can thus not be solved in an efficient way. In order to alleviate this issue, the goal of this thesis is to investigate the application of machine learning approaches to a special version of a placement problem, namely SDN controller placement. Since this problem can be solved extensively in a reasonably time frame, it is possible to evaluate the machine learning approach to a common ground truth and generate a reasonable amount of training data for the machine learning model.
  @mastersthesis{info3-master-2017-15, abstract = {Softwarization is a crucial part of modern and next generation networks, increasing flexibility, scalability and efficiency. However, new challenges regarding the placement of entities like SDN controllers or virtual network functions need to be addressed in order to reap those benefits. Unfortunately, most of these problems are NP-hard and can thus not be solved in an efficient way. In order to alleviate this issue, the goal of this thesis is to investigate the application of machine learning approaches to a special version of a placement problem, namely SDN controller placement. Since this problem can be solved extensively in a reasonably time frame, it is possible to evaluate the machine learning approach to a common ground truth and generate a reasonable amount of training data for the machine learning model.}, author = {Supervisor: Geissler, Stefan}, school = {University of Wuerzburg}, title = {Investigating the Feasibility of Machine Learning for Placement Problems in Softwarized Networks}, year = 2017 }
• Stulier, N.: Evaluation of Cranial Deformations Using Crowdsourcing, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2017-24, author = {Stulier, Norman}, month = 4, school = {University of Würzburg}, title = {Evaluation of Cranial Deformations Using Crowdsourcing}, year = 2017 }
• Supervisor: Dinh-Xuan, L.: Developing NFVs for QoE Monitoring, (2017).
  [ Abstract ] [ BibTeX ]
   
  Quality of Experience (QoE) perceived by the users is an important metric in delivering services over Internet. To secure a high users' satisfaction with such services, the providers would need to know the level of QoE measured at the client side in order to improve the services accordingly. This can be achieved by using the Network Function Virtualization (NFV) paradigm.
  @mastersthesis{info3-master-2017-3, abstract = {Quality of Experience (QoE) perceived by the users is an important metric in delivering services over Internet. To secure a high users' satisfaction with such services, the providers would need to know the level of QoE measured at the client side in order to improve the services accordingly. This can be achieved by using the Network Function Virtualization (NFV) paradigm.}, author = {Supervisor: Dinh-Xuan, Lam}, school = {University of Würzburg}, title = {Developing NFVs for QoE Monitoring}, year = 2017 }
• Borchert, K., Hirth, M., Schnitzer, S., Rensing, C.: Impact of Task Recommendation Systems in Crowdsourcing Platforms. Workshop on Responsible Recommendation at RecSys 2017. , Como, Italy (2017).
  [ BibTeX ]
   
  @inproceedings{info3-inproceedings-2017-17, address = {Como, Italy}, author = {Borchert, Kathrin and Hirth, Matthias and Schnitzer, Steffen and Rensing, Christoph}, booktitle = {Workshop on Responsible Recommendation at RecSys 2017}, month = 8, title = {Impact of Task Recommendation Systems in Crowdsourcing Platforms}, year = 2017 }
• Seufert, M.: Concept and Implementation of Video QoE Measurements in a Mobile Broadband Testbed. , IEEE/IFIP Workshop on Mobile Network Measurement (MNM’17), Dublin, Ireland (2017).
  [ BibTeX ]
   
  @presentation{info3-presentation-2017-5, address = {IEEE/IFIP Workshop on Mobile Network Measurement (MNM’17), Dublin, Ireland}, author = {Seufert, Michael}, month = 6, title = {Concept and Implementation of Video QoE Measurements in a Mobile Broadband Testbed}, year = 2017 }
• Seufert, M.: EdgeNetworkCloudSim: Placement of Service Chains in Edge Clouds Using NetworkCloudSim. , 1st IEEE International Workshop on Network Programmability - From the Data Center to the Ground (NetFoG), Bologna, Italy (2017).
  [ BibTeX ]
   
  @presentation{info3-presentation-2017-6, address = {1st IEEE International Workshop on Network Programmability - From the Data Center to the Ground (NetFoG), Bologna, Italy}, author = {Seufert, Michael}, month = 7, title = {EdgeNetworkCloudSim: Placement of Service Chains in Edge Clouds Using NetworkCloudSim}, year = 2017 }
• van Dijk, T.C., Lipp, F., Markfelder, P., Wolff, A.: Computing Storyline Visualizations with Few Block Crossings. In: Frati, F. und Ma, K.-L. (hrsg.) Proc. 25th Int. Sympos. Graph Drawing Network Vis. (GD'17). Springer-Verlag (2017).
  [ BibTeX ]
   
  @inproceedings{dlmw-csvfbc-GD2017, author = {van Dijk, Thomas C. and Lipp, Fabian and Markfelder, Peter and Wolff, Alexander}, booktitle = {Proc. 25th Int. Sympos. Graph Drawing Network Vis. (GD'17)}, editor = {Frati, Fabrizio and Ma, Kwan-Liu}, note = {to appear}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Computing Storyline Visualizations with Few Block Crossings}, year = 2017 }
• Tscharn, R., Latoschik, M.E., Hurtienne, J.: "Stop over There" – Natural Gesture and Speech Interaction for Non-Critical Spontaneous Intervention in Autonomous Driving. Proceedings of the 19th ACM International Conference on Multimodal Interaction (ICMI 2017). ACM (2017).
  [ Abstract ] [ BibTeX ]
   
  We propose a novel multimodal intervention strategy for Non-Critical Spontaneous Situations (NCSSs) in autonomous driving. The strategy combines speech and deictic gestures to instruct the car about desired interventions which include spatial references to the current car’s and hence driver’s environment (e.g., “stop over [pointing] there” or “take [pointing] this parking lot”). Speech allows for specifying a large number of maneuvers and functions in the car (e.g., stop, park, etc.), whereas deictic gestures provide a natural way of indicating spatial discourse referents used in these interventions (e.g., near this tree, that parking lot, etc.). Hence, advantages of each modality are exploited. Our multimodal system also supports a semi-immersive Virtual Reality enhanced by Semantic Entities to realize and test the proposed NCSS intervention strategy. The evaluation confirmed our approach to be more natural and intuitive, and also less cognitively demanding com- pared to a combination of speech and touch, a combination that could be seen as a straight-forward alternative to our approach due to already existing and available in-car touch screens.
  @inproceedings{tscharn2017there, abstract = {We propose a novel multimodal intervention strategy for Non-Critical Spontaneous Situations (NCSSs) in autonomous driving. The strategy combines speech and deictic gestures to instruct the car about desired interventions which include spatial references to the current car’s and hence driver’s environment (e.g., “stop over [pointing] there” or “take [pointing] this parking lot”). Speech allows for specifying a large number of maneuvers and functions in the car (e.g., stop, park, etc.), whereas deictic gestures provide a natural way of indicating spatial discourse referents used in these interventions (e.g., near this tree, that parking lot, etc.). Hence, advantages of each modality are exploited. Our multimodal system also supports a semi-immersive Virtual Reality enhanced by Semantic Entities to realize and test the proposed NCSS intervention strategy. The evaluation confirmed our approach to be more natural and intuitive, and also less cognitively demanding com- pared to a combination of speech and touch, a combination that could be seen as a straight-forward alternative to our approach due to already existing and available in-car touch screens.}, author = {Tscharn, Robert and Latoschik, Marc Erich and Hurtienne, Jörn}, booktitle = {Proceedings of the 19th ACM International Conference on Multimodal Interaction (ICMI 2017)}, note = {Accepted, to be published}, organization = {ACM}, title = {"Stop over There" – Natural Gesture and Speech Interaction for Non-Critical Spontaneous Intervention in Autonomous Driving}, year = 2017 }
• Zoller, D., Doerfel, S., Pölitz, C., Hotho, A.: Leveraging User-Interactions for Time-Aware Tag Recommendations. Proceedings of the Workshop on Temporal Reasoning in Recommender Systems (2017).
  [ BibTeX ]
   
  @inproceedings{zoller2017leveraging, author = {Zoller, Daniel and Doerfel, Stephan and Pölitz, Christian and Hotho, Andreas}, booktitle = {Proceedings of the Workshop on Temporal Reasoning in Recommender Systems}, series = {CEUR Workshop Proceedings}, title = {Leveraging User-Interactions for Time-Aware Tag Recommendations}, year = 2017 }
• Supervisor: Dinh-Xuan, L.: Extend the OpenVolcano Cloud Architecture, (2017).
  [ Abstract ] [ BibTeX ]
   
  OpenVolcano is an open source cloud platform. This provides components, modules to implement a private cloud architecture and a personal cloud as well.
  @mastersthesis{info3-praktikum-2017-4, abstract = {OpenVolcano is an open source cloud platform. This provides components, modules to implement a private cloud architecture and a personal cloud as well.}, author = {Supervisor: Dinh-Xuan, Lam}, school = {University of Würzburg}, title = {Extend the OpenVolcano Cloud Architecture}, year = 2017 }
• Zach, O., Seufert, M., Hirth, M., Slanina, M., Tran-Gia, P.: On Use of Crowdsourcing for H.264/AVC and H.265/HEVC Video Quality Evaluation. Radioelektronika. , Brno, Czech Republic (2017).
  [ Abstract ] [ BibTeX ]
   
  Crowdsourcing has become a popular method in the field of video quality evaluation. Gathering the opinion of the users using crowdsourcing is quick and relatively cheap but such a study has to be designed very carefully in order to give relevant results. So far, the majority of the QoE studies using crowdsourcing has been focusing on the performance of H.264/AVC algorithm in different situations (such as encoder settings, stalling effects, etc). Modern video coding methods, however, are only rarely tested using the crowdsourcing approach. We designed a study comparing the performance of both H.264/AVC and H.265/HEVC standards in the crowdsourcing environment. We deal with the possibilities of delivering and presenting the HEVC encoded content to the participants of the crowdsourcing study and potential challenges. Finally, the study was performed using Microworkers platform and gathered results are then compared with three different objective video quality metrics.
  @inproceedings{info3-inproceedings-2017-7, abstract = {Crowdsourcing has become a popular method in the field of video quality evaluation. Gathering the opinion of the users using crowdsourcing is quick and relatively cheap but such a study has to be designed very carefully in order to give relevant results. So far, the majority of the QoE studies using crowdsourcing has been focusing on the performance of H.264/AVC algorithm in different situations (such as encoder settings, stalling effects, etc). Modern video coding methods, however, are only rarely tested using the crowdsourcing approach. We designed a study comparing the performance of both H.264/AVC and H.265/HEVC standards in the crowdsourcing environment. We deal with the possibilities of delivering and presenting the HEVC encoded content to the participants of the crowdsourcing study and potential challenges. Finally, the study was performed using Microworkers platform and gathered results are then compared with three different objective video quality metrics.}, address = {Brno, Czech Republic}, author = {Zach, Ondrej and Seufert, Michael and Hirth, Matthias and Slanina, Martin and Tran-Gia, Phuoc}, booktitle = {Radioelektronika}, month = 4, title = {On Use of Crowdsourcing for H.264/AVC and H.265/HEVC Video Quality Evaluation}, year = 2017 }
• Loh, F.: Performance Evaluation of Service Chains in Cloud Networks Using Discrete-Time Analysis, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2017-6, author = {Loh, Frank}, school = {University of Würzburg}, title = {Performance Evaluation of Service Chains in Cloud Networks Using Discrete-Time Analysis}, year = 2017 }
• Das, A., Fleszar, K., Kobourov, S.G., Spoerhase, J., Veeramoni, S., Wolff, A.: Approximating the Generalized Minimum Manhattan Network Problem. Algorithmica. (2017).
  [ Abstract ] [ BibTeX ] [ URL ] [ DOI ]
   
  We consider the emphgeneralized minimum Manhattan network problem (GMMN). The input to this problem is a set \($R$\) of \($n$\) pairs of terminals, which are points in \($\mathbbR^2$\). The goal is to find a minimum-length rectilinear network that connects every pair in \($R$\) by a emphManhattan path, that is, a path of axis-parallel line segments whose total length equals the pair's Manhattan distance. This problem is a natural generalization of the extensively studied emphminimum Manhattan network problem (MMN) in which \($R$\) consists of all possible pairs of terminals. Another important special case is the well-known emphrectilinear Steiner arborescence problem (RSA). As a generalization of these problems, GMMN is NP-hard. No approximation algorithms are known for general GMMN. par We obtain an \($O(\log n)$\)-approximation algorithm for GMMN. Our solution is based on a stabbing technique, a novel way of attacking Manhattan network problems. Some parts of our algorithm generalize to higher dimensions, yielding a simple \($O(\log^d+1 n)$\)- approximation algorithm for the problem in arbitrary fixed dimension~\($d$\). As a corollary, we obtain an exponential improvement upon the previously best \($O(n^\epsilon)$\)-ratio for MMN in \($d$\) dimensions [ESA 2011]. En route, we show that an existing \($O(\log n)$\)-approximation algorithm for 2D-RSA generalizes to higher dimensions.
  @article{dfksvw-agmmnp-Algorithmica17, abstract = {We consider the emphgeneralized minimum Manhattan network problem (GMMN). The input to this problem is a set \($R$\) of \($n$\) pairs of terminals, which are points in \($\mathbbR^2$\). The goal is to find a minimum-length rectilinear network that connects every pair in \($R$\) by a emphManhattan path, that is, a path of axis-parallel line segments whose total length equals the pair's Manhattan distance. This problem is a natural generalization of the extensively studied emphminimum Manhattan network problem (MMN) in which \($R$\) consists of all possible pairs of terminals. Another important special case is the well-known emphrectilinear Steiner arborescence problem (RSA). As a generalization of these problems, GMMN is NP-hard. No approximation algorithms are known for general GMMN. par We obtain an \($O(\log n)$\)-approximation algorithm for GMMN. Our solution is based on a stabbing technique, a novel way of attacking Manhattan network problems. Some parts of our algorithm generalize to higher dimensions, yielding a simple \($O(\log^d+1 n)$\)- approximation algorithm for the problem in arbitrary fixed dimension~\($d$\). As a corollary, we obtain an exponential improvement upon the previously best \($O(n^\epsilon)$\)-ratio for MMN in \($d$\) dimensions [ESA 2011]. En route, we show that an existing \($O(\log n)$\)-approximation algorithm for 2D-RSA generalizes to higher dimensions.}, author = {Das, Aparna and Fleszar, Krzysztof and Kobourov, Stephen G. and Spoerhase, Joachim and Veeramoni, Sankar and Wolff, Alexander}, journal = {Algorithmica}, note = {To appear.}, title = {Approximating the Generalized Minimum Manhattan Network Problem}, year = 2017 }
• Pfaff, B.: Evaluation of a Distributed Control Plane for Managing Heterogeneous SDN and Legacy Networks, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2017-12, author = {Pfaff, Benedikt}, month = 5, school = {University of Würzburg}, title = {Evaluation of a Distributed Control Plane for Managing Heterogeneous SDN and Legacy Networks}, year = 2017 }
• Sommer, M.: Implementation of an OpenFlow Fuzzing Framework, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-praktikum-2017-7, author = {Sommer, Manuel}, school = {University of Würzburg}, title = {Implementation of an OpenFlow Fuzzing Framework}, year = 2017 }
• Ott, M.: Extraction of SDN Device Fingerprints for Enhancing the Network Security, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-praktikum-2017-8, author = {Ott, Michael}, school = {University of Würzburg}, title = {Extraction of SDN Device Fingerprints for Enhancing the Network Security}, year = 2017 }
• Gray, N., Lorenz, C., Müssig, A., Gebert, S., Zinner, T., Tran-Gia, P.: A Priori State Synchronization for Fast Failover of Stateful Firewall VNFs. Workshop on Software-Defined Networking and Network Function Virtualization for Flexible Network Management (SDNFlex 2017). , Göttingen, Germany (2017).
  [ Abstract ] [ BibTeX ]
   
  Network Functions Virtualization (NFV) replaces physical middleboxes with software instances running network functions in cloud environments. To support this new paradigm, it is necessary to port the code basis from highly specialized hardware devices to virtual machines running on COTS hard- ware. In order to fully exploit the inherent capabilities of cloud environments it is further necessary to redesign the software to support a large amount of distributed, cooperating function instances instead of single, isolated and monolithic instances. This development can be observed for network functions like stateful firewalling. Until now, available software firewalls lack support for active/active operation in clustered environments, which hinders horizontal scalability. This is due to the fact that the required synchronization of connection states among the cluster’s instances is an impediment that still has to be resolved. Therefore, this work investigates different synchronization strategies and mechanisms, which allow to share connection states among the cluster to maintain scalability and high-availability
  @inproceedings{info3-inproceedings-2017-2, abstract = {Network Functions Virtualization (NFV) replaces physical middleboxes with software instances running network functions in cloud environments. To support this new paradigm, it is necessary to port the code basis from highly specialized hardware devices to virtual machines running on COTS hard- ware. In order to fully exploit the inherent capabilities of cloud environments it is further necessary to redesign the software to support a large amount of distributed, cooperating function instances instead of single, isolated and monolithic instances. This development can be observed for network functions like stateful firewalling. Until now, available software firewalls lack support for active/active operation in clustered environments, which hinders horizontal scalability. This is due to the fact that the required synchronization of connection states among the cluster’s instances is an impediment that still has to be resolved. Therefore, this work investigates different synchronization strategies and mechanisms, which allow to share connection states among the cluster to maintain scalability and high-availability}, address = {Göttingen, Germany}, author = {Gray, Nicholas and Lorenz, Class and Müssig, Alexander and Gebert, Steffen and Zinner, Thomas and Tran-Gia, Phuoc}, booktitle = {Workshop on Software-Defined Networking and Network Function Virtualization for Flexible Network Management (SDNFlex 2017)}, title = {A Priori State Synchronization for Fast Failover of Stateful Firewall VNFs}, year = 2017 }
• Supervisor: Nguyen-Ngoc, A.: Evaluation of Topology Discovery Mechanisms for SDN Networks, (2017).
  [ Abstract ] [ BibTeX ]
   
  In SDN environment, topology discovery is one of the most important services, provides a centralized global view of the whole network and is primary step for other network applications (e.g., traffic engineering, network/host monitoring...). In this thesis, the student focuses on the comparison of Discovery Topology Time between SDN controller (ONOS, Opendaylight) by developing an additional module which allows to calculate the time a controller needs to discover network topology. As well as compare the results with others SDN benchmarking tools (TESTON, OFCProble). Contact: anh.nguyen@informatik.uni-wuerzburg.de
  @mastersthesis{info3-bachelor-2017-13, abstract = {In SDN environment, topology discovery is one of the most important services, provides a centralized global view of the whole network and is primary step for other network applications (e.g., traffic engineering, network/host monitoring...). In this thesis, the student focuses on the comparison of Discovery Topology Time between SDN controller (ONOS, Opendaylight) by developing an additional module which allows to calculate the time a controller needs to discover network topology. As well as compare the results with others SDN benchmarking tools (TESTON, OFCProble). Contact: anh.nguyen@informatik.uni-wuerzburg.de}, author = {Supervisor: Nguyen-Ngoc, Anh}, month = 4, school = {University of Würzburg}, title = {Evaluation of Topology Discovery Mechanisms for SDN Networks}, year = 2017 }
• Supervisor: Borchert, K.: Analysis and Correlation of objective and subjective Performance Data of an Enterprise Application, (2017).
  [ Abstract ] [ BibTeX ]
   
  Contact: kathrin.borchert@informatik.uni-wuerzburg.de
  @mastersthesis{info3-praktikum-2017-9, abstract = {Contact: kathrin.borchert@informatik.uni-wuerzburg.de}, author = {Supervisor: Borchert, Kathrin}, school = {University of Wuerzburg}, title = {Analysis and Correlation of objective and subjective Performance Data of an Enterprise Application}, year = 2017 }
• Dinh-Xuan, L., Seufert, M., Wamser, F., Tran-Gia, P.: Study on the Accuracy of QoE Monitoring for HTTP Adaptive Video Streaming Using VNF. 1st IFIP/IEEE International Workshop on Quality of Experience Management (QoE-Management). , Lisbon, Portugal (2017).
  [ Abstract ] [ BibTeX ]
   
  The fast growth of HTTP video streaming is responsible for a huge amount of traffic over the past few years. Due to the variety and popularity of video content, more and more people are watching videos on the smart TV or on mobile devices. As a result, a potential market is emerging for video providers, which can significantly increase their revenues. In order to offer users a good experience, adaptive video streaming has been introduced to adapt the video quality to the network conditions. Nevertheless, it is still difficult for the network operators to assess the actual video quality on the device of the users and therefore they can not react to improve the service on the network. In this work, we propose a Virtual Network Function (VNF) to monitor the Quality of Experience (QoE) for online video service in the network. To conduct the study, on the one hand, we design a VNF monitoring to measure the video quality and estimate the QoE at the client machine. Our function is placed in two locations nearby and far away from the user to analyze the impact of geographical placement of the VNF on its performance. On the other hand, we set up a local testbed to examine the functional operation and measure the actual video buffer from a client web browser directly to validate the accuracy of the function. Our findings show that with respect to function placement, the VNF has high accuracy in estimating the QoE if it is deployed at the edge network close to the user. However, the VNF does not perform well when it operates far away from the users, e.g., at data centers. These insights help network vendors to more closely monitor the quality of the videos streamed to their customers.
  @inproceedings{info3-inproceedings-2017-3, abstract = {The fast growth of HTTP video streaming is responsible for a huge amount of traffic over the past few years. Due to the variety and popularity of video content, more and more people are watching videos on the smart TV or on mobile devices. As a result, a potential market is emerging for video providers, which can significantly increase their revenues. In order to offer users a good experience, adaptive video streaming has been introduced to adapt the video quality to the network conditions. Nevertheless, it is still difficult for the network operators to assess the actual video quality on the device of the users and therefore they can not react to improve the service on the network. In this work, we propose a Virtual Network Function (VNF) to monitor the Quality of Experience (QoE) for online video service in the network. To conduct the study, on the one hand, we design a VNF monitoring to measure the video quality and estimate the QoE at the client machine. Our function is placed in two locations nearby and far away from the user to analyze the impact of geographical placement of the VNF on its performance. On the other hand, we set up a local testbed to examine the functional operation and measure the actual video buffer from a client web browser directly to validate the accuracy of the function. Our findings show that with respect to function placement, the VNF has high accuracy in estimating the QoE if it is deployed at the edge network close to the user. However, the VNF does not perform well when it operates far away from the users, e.g., at data centers. These insights help network vendors to more closely monitor the quality of the videos streamed to their customers.}, address = {Lisbon, Portugal}, author = {Dinh-Xuan, Lam and Seufert, Michael and Wamser, Florian and Tran-Gia, Phuoc}, booktitle = {1st IFIP/IEEE International Workshop on Quality of Experience Management (QoE-Management)}, month = 5, title = {Study on the Accuracy of QoE Monitoring for HTTP Adaptive Video Streaming Using VNF}, year = 2017 }
• Kullmann, P., Eyck, R., Latoschik, M.E., Roth, D.: Augmenting Human Gaze in Avatar-Mediated Communication. (2017).
  [ Abstract ] [ BibTeX ]
   
  Future social virtual environments will allow machines to transcend face-to-face interaction and manipulate human social interactions in computer-mediated communication. Whereas in real-world interactions we use our real bodies as means to mediate our message and communicate additional information, in virtual environments we are represented by avatars. Progressing from Mori’s Uncanny Valley theory [1] and similar to "the medium is the message" [2] approaches, many research activities have investigated the impact of manipulating the appearance realism of virtual characters [3]. However, the impact of behavioural realism and its potential augmentation in avatar-mediated communication, is not fully understood. The present work in progress investigates the impact of behaviour most likely disclosing human comprehension: gaze. Gaze cues are reciprocal nonverbal signals that are used to both detect information about interlocutors and communicate to them [4]. Where our conversational partners focus their attention, is relevant for building rapport and interaction naturalness [5]. In an avatar-mediated communication system prototype we examine how augmenting avatars' gaze behaviour influences the gaze behaviour of humans communicating via avatars and their rating of the communication quality. We let our avatars make eye contact whenever the human it is facing speaks. We hypothesise that this will increase the quality of the social interaction and will lead to the participants acting more attentive with regard to their gaze behaviour. Furthermore, we aim to identify a quantitative impact between the degree of aforementioned manipulation and the acceptance of the communicative counterpart as human or machine. While participants adjusting their gaze behaviour in relation to the avatar augmentation implies great opportunities for using avatar-mediated communication in therapeutic applications, its ethical implications have to be addressed.
  @presentation{kullmann2017augmenting, abstract = {Future social virtual environments will allow machines to transcend face-to-face interaction and manipulate human social interactions in computer-mediated communication. Whereas in real-world interactions we use our real bodies as means to mediate our message and communicate additional information, in virtual environments we are represented by avatars. Progressing from Mori’s Uncanny Valley theory [1] and similar to "the medium is the message" [2] approaches, many research activities have investigated the impact of manipulating the appearance realism of virtual characters [3]. However, the impact of behavioural realism and its potential augmentation in avatar-mediated communication, is not fully understood. The present work in progress investigates the impact of behaviour most likely disclosing human comprehension: gaze. Gaze cues are reciprocal nonverbal signals that are used to both detect information about interlocutors and communicate to them [4]. Where our conversational partners focus their attention, is relevant for building rapport and interaction naturalness [5]. In an avatar-mediated communication system prototype we examine how augmenting avatars' gaze behaviour influences the gaze behaviour of humans communicating via avatars and their rating of the communication quality. We let our avatars make eye contact whenever the human it is facing speaks. We hypothesise that this will increase the quality of the social interaction and will lead to the participants acting more attentive with regard to their gaze behaviour. Furthermore, we aim to identify a quantitative impact between the degree of aforementioned manipulation and the acceptance of the communicative counterpart as human or machine. While participants adjusting their gaze behaviour in relation to the avatar augmentation implies great opportunities for using avatar-mediated communication in therapeutic applications, its ethical implications have to be addressed.}, author = {Kullmann, Peter and Eyck, Roman and Latoschik, Marc Erich and Roth, Daniel}, howpublished = {Poster presentation at the Interdisciplinary Colloge in Günne, Creativity and Intelligence in Brains and Machines, 2017}, title = {Augmenting Human Gaze in Avatar-Mediated Communication}, year = 2017 }
• Wamser, F., Loh, F., Bruschi, R., Lago, P., Seufert, M., Tran-Gia, P.: Dynamic Cloud Service Placement for Live Video Streaming with a Remote-Controlled Drone, (2017).
  [ Abstract ] [ BibTeX ]
   
  The continuous growth of Internet content, applications and services has led to ever more demanding requirements in the networks. To meet this, there have been significant developments in the migration of applications and services towards the cloud. The cloud not only provides applications, but also offers dynamic adaptability, scalability, and optimization with respect to the location of the application by migrating storage and application containers. In particular, cloud services can typically be placed and orchestrated at a variety of locations in the cloud. This demonstration shows a dynamic placement of a cloud service with video streaming and real-time control commands for a remote-controlled drone. We control a drone with the help of a cloud service which, in addition to the control commands, also returns a camera image to the operator. The requirements of this cloud application are groundbreaking. The camera requires high data rates from the drone to the cloud and from the cloud to the operator, so that the image can be transmitted in acceptable quality. For the control of the drone, a short delay must also be given in the direction of the drone so that the control can be carried out in real time.
  @misc{info3-demo-2017-1, abstract = {The continuous growth of Internet content, applications and services has led to ever more demanding requirements in the networks. To meet this, there have been significant developments in the migration of applications and services towards the cloud. The cloud not only provides applications, but also offers dynamic adaptability, scalability, and optimization with respect to the location of the application by migrating storage and application containers. In particular, cloud services can typically be placed and orchestrated at a variety of locations in the cloud. This demonstration shows a dynamic placement of a cloud service with video streaming and real-time control commands for a remote-controlled drone. We control a drone with the help of a cloud service which, in addition to the control commands, also returns a camera image to the operator. The requirements of this cloud application are groundbreaking. The camera requires high data rates from the drone to the cloud and from the cloud to the operator, so that the image can be transmitted in acceptable quality. For the control of the drone, a short delay must also be given in the direction of the drone so that the control can be carried out in real time.}, address = {Lisbon, Portugal}, author = {Wamser, Florian and Loh, Frank and Bruschi, Roberto and Lago, Paolo and Seufert, Michael and Tran-Gia, Phuoc}, booktitle = {15th IFIP/IEEE International Symposium on Integrated Network Management (IM)}, month = 5, title = {Dynamic Cloud Service Placement for Live Video Streaming with a Remote-Controlled Drone}, year = 2017 }
• Roth, D., Waldow, K., Latoschik, M.E., Fuhrmann, A., Bente, G.: Socially Immersive Avatar-Based Communication. Proceedings of the 24th IEEE Virtual Reality (IEEE VR) conference 2017 (2017).
  [ BibTeX ]
   
  @inproceedings{roth2017socially, author = {Roth, Daniel and Waldow, Kristoffer and Latoschik, Marc Erich and Fuhrmann, Arnulph and Bente, Gary}, booktitle = {Proceedings of the 24th IEEE Virtual Reality (IEEE VR) conference 2017}, title = {Socially Immersive Avatar-Based Communication}, year = 2017 }
• Waigand, P.: Predictive Modeling of Video Spreading in Online Social Networks, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2017-14, author = {Waigand, Philipp}, month = 8, school = {University of Würzburg}, title = {Predictive Modeling of Video Spreading in Online Social Networks}, year = 2017 }
• Wehner, N.: Unsupervised QoE Field Study for Mobile YouTube Video Streaming with YoMoApp, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-praktikum-2017-10, author = {Wehner, Nikolas}, month = 3, school = {University of Würzburg}, title = {Unsupervised QoE Field Study for Mobile YouTube Video Streaming with YoMoApp}, year = 2017 }
• Supervisor: Schwarzmann, S.: Impact of Imprecise Application Information on the Performance of Application-Network Management Approaches, (2017).
  [ Abstract ] [ BibTeX ]
   
  Contact: susanna.schwarzmann@informatik.uni-wuerzburg.de In order to enhance Quality of Experience (QoE), several approaches are going towards an adaptation of the network in order to meet an application's requirements (Application-Network Management approaches). To do so, these mechanisms often rely on information from the application (e.g. video quality or buffer level). The goal in this thesis is to evaluate the impact of imprecise application information, e.g. due to inaccurate prediction by a machine learning algorithm, on the performance of such a mechanism.
  @mastersthesis{info3-bachelor-2017-17, abstract = {Contact: susanna.schwarzmann@informatik.uni-wuerzburg.de In order to enhance Quality of Experience (QoE), several approaches are going towards an adaptation of the network in order to meet an application's requirements (Application-Network Management approaches). To do so, these mechanisms often rely on information from the application (e.g. video quality or buffer level). The goal in this thesis is to evaluate the impact of imprecise application information, e.g. due to inaccurate prediction by a machine learning algorithm, on the performance of such a mechanism.}, author = {Supervisor: Schwarzmann, Susanna}, school = {University of Wuerzburg}, title = {Impact of Imprecise Application Information on the Performance of Application-Network Management Approaches}, year = 2017 }
• Niebling, F., Münster, S., Friedrichs, K., Henze, F., Kröber, C., Bruschke, J.: Zugänglichkeit und dauerhafte Nutzbarkeit historischer Bildrepositorien für Forschung und Vermittlung. In: Stolz, M. (hrsg.) Digital Humanities im deutschsprachigen Raum (DHd) (2017).
  [ BibTeX ]
   
  @inproceedings{niebling2017zugnglichkeit, author = {Niebling, Florian and Münster, Sander and Friedrichs, Kristina and Henze, Frank and Kröber, Cindy and Bruschke, Jonas}, booktitle = {Digital Humanities im deutschsprachigen Raum (DHd)}, editor = {Stolz, Michael}, title = {Zugänglichkeit und dauerhafte Nutzbarkeit historischer Bildrepositorien für Forschung und Vermittlung}, year = 2017 }
• Seufert, M., Moldovan, C., Burger, V., Hoßfeld, T.: Applicability and Limitations of a Simple WiFi Hotspot Model for Cities. 13th International Conference on Network and Service Management (CNSM). , Tokio, Japan (2017).
  [ Abstract ] [ BibTeX ]
   
  Offloading mobile Internet data via WiFi has emerged as an omnipresent trend. WiFi networks are already widely deployed by many private and public institutions (e.g., libraries, cafes, restaurants) but also by commercial services to provide alternative Internet access for their customers and to mitigate the load on mobile networks. Moreover, smart cities start to install WiFi infrastructure for current and future civic services, e.g., based on sensor networks or the Internet of Things. A simple model for the distribution of WiFi hotspots in an urban environment is presented. The hotspot locations are modeled with a uniform distribution of the angle and an exponential distribution of the distance, which is truncated to the city limits. We compare the characteristics of this model in detail to the real distributions. Moreover, we show the applicability and the limitations of this model, and the results suggest that the model can be used in scenarios, which do not require an accurate spatial collocation of the hotspots, such as offloading potential, coverage, or signal strength.
  @inproceedings{info3-inproceedings-2017-19, abstract = {Offloading mobile Internet data via WiFi has emerged as an omnipresent trend. WiFi networks are already widely deployed by many private and public institutions (e.g., libraries, cafes, restaurants) but also by commercial services to provide alternative Internet access for their customers and to mitigate the load on mobile networks. Moreover, smart cities start to install WiFi infrastructure for current and future civic services, e.g., based on sensor networks or the Internet of Things. A simple model for the distribution of WiFi hotspots in an urban environment is presented. The hotspot locations are modeled with a uniform distribution of the angle and an exponential distribution of the distance, which is truncated to the city limits. We compare the characteristics of this model in detail to the real distributions. Moreover, we show the applicability and the limitations of this model, and the results suggest that the model can be used in scenarios, which do not require an accurate spatial collocation of the hotspots, such as offloading potential, coverage, or signal strength.}, address = {Tokio, Japan}, author = {Seufert, Michael and Moldovan, Christian and Burger, Valentin and Hoßfeld, Tobias}, booktitle = {13th International Conference on Network and Service Management (CNSM)}, month = 11, title = {Applicability and Limitations of a Simple WiFi Hotspot Model for Cities}, year = 2017 }
• Rojkov, M., Aschenbrenner, D., Schilling, K., Latoschik, M.E.: Tracking Algorithms for Cooperative Telemaintenance Repair Operations. Proceedings of the 20th World Congress of the International Federation of Automatic Control (IFAC) (2017).
  [ BibTeX ]
   
  @inproceedings{rojkov2017tracking, author = {Rojkov, Michael and Aschenbrenner, Doris and Schilling, Klaus and Latoschik, Marc Erich}, booktitle = {Proceedings of the 20th World Congress of the International Federation of Automatic Control (IFAC)}, note = {To appear}, title = {Tracking Algorithms for Cooperative Telemaintenance Repair Operations}, year = 2017 }
• Bekos, M.A., van Dijk, T.C., Fink, M., Kindermann, P., Kobourov, S.G., Pupyrev, S., Spoerhase, J., Wolff, A.: Improved Approximation Algorithms for Box Contact Representations. Algorithmica. 77, 902--920 (2017).
  [ BibTeX ] [ URL ] [ DOI ]
   
  @article{bekos-etal17:approx-box-contact, author = {Bekos, Michael A. and van Dijk, Thomas C. and Fink, Martin and Kindermann, Philipp and Kobourov, Stephen G. and Pupyrev, Sergey and Spoerhase, Joachim and Wolff, Alexander}, journal = {Algorithmica}, number = 3, pages = {902--920}, title = {Improved Approximation Algorithms for Box Contact Representations}, volume = 77, year = 2017 }
• Das, A., Fleszar, K., Kobourov, S., Spoerhase, J., Veeramoni, S., Wolff, A.: Approximating the Generalized Minimum Manhattan Network Problem. Algorithmica. (2017).
  [ BibTeX ]
   
  @article{das-etal17:approximating-gmmn, author = {Das, Aparna and Fleszar, Krzysztof and Kobourov, Stephen and Spoerhase, Joachim and Veeramoni, Sankar and Wolff, Alexander}, journal = {Algorithmica}, note = {accepted}, title = {Approximating the Generalized Minimum Manhattan Network Problem}, year = 2017 }
• Byrka, J., Pensyl, T., Rybicki, B., Spoerhase, J., Srinivasan, A., Trinh, K.: An Improved Approximation Algorithm for Knapsack Median Using Sparsification. Algorithmica. (2017).
  [ BibTeX ]
   
  @article{byrka-etal:knapsack-journal, author = {Byrka, Jaroslaw and Pensyl, Thomas and Rybicki, Bartosz and Spoerhase, Joachim and Srinivasan, Aravind and Trinh, Khoa}, journal = {Algorithmica}, note = {accepted}, title = {An Improved Approximation Algorithm for Knapsack Median Using Sparsification}, year = 2017 }
• Geissler, S., Gebert, S., Herrnleben, S., Zinner, T., Bauer, R., Jarschel, M.: TableVisor 2.0: Towards Full-Featured, Scalable and Hardware-Independent Multi Table Processing. NetSoft 2017, Best Student Paper Award (2017).
  [ Abstract ] [ BibTeX ]
   
  Modern Software Defined Networking (SDN) appli- cations rely on sophisticated packet processing. However, there is a mismatch between control plane requirements and data plane capabilities caused by increasing hardware heterogeneity. To overcome this challenge, we propose TableVisor, a proxy-layer for the OpenFlow control channel that enables the flexible and scalable abstraction of multiple physical devices into one emu- lated data plane switch that meets the requirements of the control plane application. TableVisor registers with the SDN controller as a single switch with use-case specific capabilities. It translates the instructions and rules from the control application towards the appropriate physical device where they are executed. In this paper, we present the updated architecture and functionality of TableVisor as well as first evaluation results based on testbed experiments.
  @inproceedings{info3-inproceedings-2017-4, abstract = {Modern Software Defined Networking (SDN) appli- cations rely on sophisticated packet processing. However, there is a mismatch between control plane requirements and data plane capabilities caused by increasing hardware heterogeneity. To overcome this challenge, we propose TableVisor, a proxy-layer for the OpenFlow control channel that enables the flexible and scalable abstraction of multiple physical devices into one emu- lated data plane switch that meets the requirements of the control plane application. TableVisor registers with the SDN controller as a single switch with use-case specific capabilities. It translates the instructions and rules from the control application towards the appropriate physical device where they are executed. In this paper, we present the updated architecture and functionality of TableVisor as well as first evaluation results based on testbed experiments.}, author = {Geissler, Stefan and Gebert, Steffen and Herrnleben, Stefan and Zinner, Thomas and Bauer, Robert and Jarschel, Michael}, booktitle = {NetSoft 2017, Best Student Paper Award}, month = 2, title = {TableVisor 2.0: Towards Full-Featured, Scalable and Hardware-Independent Multi Table Processing}, year = 2017 }
• Zinner, T., Geissler, S., Helmschrott, F., Spinsante, S., Braeken, A.: An AAL-Oriented Measurement-based Evaluation of Different HTTP-based Data Transport Protocols. International Workshop on Protocols, Applications and Platforms for Enhanced Living Environments (2017).
  [ Abstract ] [ BibTeX ]
   
  A key requirement for Active and Assisted Living (AAL) environments is the exchange of data between different communication endpoints to support wide range of services and applications. Used communication protocols need to support the bidirectional flow of information and have to be optimized with regard to security or latency constraints. To address these issues, RESTful approaches have recently gained much attention from the community. In this context, different application layer transport protocols can be used to realize the required data exchange. Besides HTTP/1.1, developed and standardized in the 1990s, new protocols like HTTP/2 and the QUIC transfer protocol my be suitable candidates. The impact of the different protocols on the overall performance for web and AAL services is still an open research question. This paper narrows this gap by conducting a measurement-based comparison of the three described protocols with regard to their performance in terms of web page loading times for Google web services.
  @inproceedings{info3-inproceedings-2017-5, abstract = {A key requirement for Active and Assisted Living (AAL) environments is the exchange of data between different communication endpoints to support wide range of services and applications. Used communication protocols need to support the bidirectional flow of information and have to be optimized with regard to security or latency constraints. To address these issues, RESTful approaches have recently gained much attention from the community. In this context, different application layer transport protocols can be used to realize the required data exchange. Besides HTTP/1.1, developed and standardized in the 1990s, new protocols like HTTP/2 and the QUIC transfer protocol my be suitable candidates. The impact of the different protocols on the overall performance for web and AAL services is still an open research question. This paper narrows this gap by conducting a measurement-based comparison of the three described protocols with regard to their performance in terms of web page loading times for Google web services.}, author = {Zinner, Thomas and Geissler, Stefan and Helmschrott, Fabian and Spinsante, Susanna and Braeken, An}, booktitle = {International Workshop on Protocols, Applications and Platforms for Enhanced Living Environments}, month = 2, title = {An AAL-Oriented Measurement-based Evaluation of Different HTTP-based Data Transport Protocols}, year = 2017 }
• Zinner, T., Geissler, S., Helmschrott, F., Burger, V.: Comparison of the Initial Delay for Video Playout Start for Different HTTP-based Transport Protocols. Workshop on Quality of Experience Management (2017).
  [ Abstract ] [ BibTeX ]
   
  This paper details a measurement study on the impact of different HTTP-based application layer protocols, namely HTTP/1, HTTP/2 and QUIC, on video streaming performance. In this context we evaluate the influence on the initial delay until video playout is started using the live version of the YouTube platform. Furthermore, we evaluate how different network parameters, i.e. bandwidth, RTTs and packet loss influence the different protocols. This work presents an verview over the characteristics of the compared protocols and presents a detailed measurement methodology on how the data has been obtained. Finally, the observed data is evaluated in the context of YouTube video streaming.
  @inproceedings{info3-inproceedings-2017-6, abstract = {This paper details a measurement study on the impact of different HTTP-based application layer protocols, namely HTTP/1, HTTP/2 and QUIC, on video streaming performance. In this context we evaluate the influence on the initial delay until video playout is started using the live version of the YouTube platform. Furthermore, we evaluate how different network parameters, i.e. bandwidth, RTTs and packet loss influence the different protocols. This work presents an verview over the characteristics of the compared protocols and presents a detailed measurement methodology on how the data has been obtained. Finally, the observed data is evaluated in the context of YouTube video streaming.}, author = {Zinner, Thomas and Geissler, Stefan and Helmschrott, Fabian and Burger, Valentin}, booktitle = {Workshop on Quality of Experience Management}, month = 2, title = {Comparison of the Initial Delay for Video Playout Start for Different HTTP-based Transport Protocols}, year = 2017 }
• Hammer, S., Kirchner, K., André, E., Lugrin, B.: Touch or Talk?: Comparing Social Robots and Tablet PCs for an Elderly Assistant Recommender System. In: Mutlu, B., Tscheligi, M., Weiss, A., und Young, J.E. (hrsg.) Proceedings of the Companion of the 2017 ACM/IEEE International Conference on Human-Robot Interaction. S. 129-130. ACM (2017).
  [ BibTeX ] [ URL ]
   
  @inproceedings{conf/hri/HammerKAL17, author = {Hammer, Stephan and Kirchner, Kim and André, Elisabeth and Lugrin, Birgit}, booktitle = {Proceedings of the Companion of the 2017 ACM/IEEE International Conference on Human-Robot Interaction}, crossref = {conf/hri/2017c}, editor = {Mutlu, Bilge and Tscheligi, Manfred and Weiss, Astrid and Young, James E.}, pages = {129-130}, publisher = {ACM}, title = {Touch or Talk?: Comparing Social Robots and Tablet PCs for an Elderly Assistant Recommender System.}, year = 2017 }
• Menne, I.M., Lugrin, B.: In the Face of Emotion: A Behavioral Study on Emotions Towards a Robot Using the Facial Action Coding System. In: Mutlu, B., Tscheligi, M., Weiss, A., und Young, J.E. (hrsg.) Companion of the 2017 ACM/IEEE International Conference on Human-Robot Interaction, HRI 2017, Vienna, Austria, March 6-9, 2017. S. 205--206 (2017).
  [ BibTeX ] [ URL ] [ DOI ]
   
  @inproceedings{DBLP:conf/hri/MenneL17, author = {Menne, Isabelle M. and Lugrin, Birgit}, booktitle = {Companion of the 2017 ACM/IEEE International Conference on Human-Robot Interaction, HRI 2017, Vienna, Austria, March 6-9, 2017}, crossref = {DBLP:conf/hri/2017c}, editor = {Mutlu, Bilge and Tscheligi, Manfred and Weiss, Astrid and Young, James E.}, pages = {205--206}, title = {In the Face of Emotion: A Behavioral Study on Emotions Towards a Robot Using the Facial Action Coding System.}, year = 2017 }
• Bocerov, M.: Video Encoding Techniques and their Impact on the Trade-off between Bitrate and Video Quality, (2017).
  [ Abstract ] [ BibTeX ]
   
  Contact: susanna.schwarzmann@informatik.uni-wuerzburg.de Video content providers like YouTube and Netflix leverage the emergence of novel techniques for video encoding. The goal of this thesis is to give an overview on currently applied techniques and to evaluate/compare their characteristics w.r.t. the resulting video quality and encoding effort.
  @mastersthesis{info3-bachelor-2017-16, abstract = {Contact: susanna.schwarzmann@informatik.uni-wuerzburg.de Video content providers like YouTube and Netflix leverage the emergence of novel techniques for video encoding. The goal of this thesis is to give an overview on currently applied techniques and to evaluate/compare their characteristics w.r.t. the resulting video quality and encoding effort.}, author = {Bocerov, Maria}, school = {University of Wuerzburg}, title = {Video Encoding Techniques and their Impact on the Trade-off between Bitrate and Video Quality}, year = 2017 }
• Supervisor: Seufert, M.: QoE Measurements for Popular Web Services in a Mobile Broadband Testbed, (2017).
  [ Abstract ] [ BibTeX ]
   
  Contact: Michael Seufert <seufert@informatik.uni-wuerzburg.de> This thesis will design and implement Quality of Experience (QoE) measurements for popular web services, such as web browsing, online social networks (e.g., Facebook), music streaming services (e.g., Spotify). The measurements are conducted in a mobile broadband testbed deployed in multiple European countries. The measurements have to integrated into the testbed, they have to be executed, and the results have to be evaluated. Thereby, the impact of the mobile networks and mobility on the QoE of the web services will be investigated.
  @mastersthesis{info3-master-2017-5, abstract = {Contact: Michael Seufert <seufert@informatik.uni-wuerzburg.de> This thesis will design and implement Quality of Experience (QoE) measurements for popular web services, such as web browsing, online social networks (e.g., Facebook), music streaming services (e.g., Spotify). The measurements are conducted in a mobile broadband testbed deployed in multiple European countries. The measurements have to integrated into the testbed, they have to be executed, and the results have to be evaluated. Thereby, the impact of the mobile networks and mobility on the QoE of the web services will be investigated.}, author = {Supervisor: Seufert, Michael}, school = {University of Würzburg}, title = {QoE Measurements for Popular Web Services in a Mobile Broadband Testbed}, year = 2017 }
• Gray, N.: Evaluation of the Impact of Network Topologies and Applications on Synchronization Strategies of Distributed SDN Controllers, (2017).
  [ Abstract ] [ BibTeX ]
   
  Software-defined Networking (SDN) separates the data from the control plane and outsources the latter to a logically centralized instance called the controller. This enables a common view of the network topology and provides a central entity for network configurations. The controller is often distributed to impose no single point of failure and to balance the load efficiently among the physical controller instances. To maintain a consistent view of the network, synchronization between the individual controller instances is required. Controller implementations can be categorized by their utilized synchronization strategy and largely fall in one of two categories, namely horizontal or hierarchical. Goal of this thesis is to evaluate the impact of the network topology and running controller applications on the performance of the controller when using different synchronization mechanisms. As access to large SDN test beds is limited the investigations will be done by simulations within the OMNeT++ framework.
  @mastersthesis{info3-bachelor-2017-18, abstract = {Software-defined Networking (SDN) separates the data from the control plane and outsources the latter to a logically centralized instance called the controller. This enables a common view of the network topology and provides a central entity for network configurations. The controller is often distributed to impose no single point of failure and to balance the load efficiently among the physical controller instances. To maintain a consistent view of the network, synchronization between the individual controller instances is required. Controller implementations can be categorized by their utilized synchronization strategy and largely fall in one of two categories, namely horizontal or hierarchical. Goal of this thesis is to evaluate the impact of the network topology and running controller applications on the performance of the controller when using different synchronization mechanisms. As access to large SDN test beds is limited the investigations will be done by simulations within the OMNeT++ framework.}, author = {Gray, Nicholas}, school = {University of Würzburg}, title = {Evaluation of the Impact of Network Topologies and Applications on Synchronization Strategies of Distributed SDN Controllers}, year = 2017 }
• Moldovan, C., Burger, V., Metzger, F., Surminski, S., Hoßfeld, T.: Viability of Wi-Fi Caches in an Era of HTTPS Prevalence. IEEE ICC'17: Bridging People, Communities, and Cultures. , Paris, France (2017).
  [ Abstract ] [ BibTeX ]
   
  Caches are often employed to better manage the ever-growing amount of global Internet traffic. Particularly, reverse proxies are often used to free up congested peering links and reduce inter-domain traffic. In addition, caches place content close to the edge, leading to lower latency which can be beneficial for many applications. In an effort to bring content even closer to end devices, home routers and public access points are now in the spotlight as a novel location for caches. Compared to CDNs, a Wi-Fi router only offers scarce storage and processing capabilities, putting an increased emphasis on resource management. In addition, a large share of traffic is transmitted through secured connections preventing the use of forward caches and other middle boxes. This paper strives to analyze how effective caching can be in public Wi-Fi routers. For this purpose, we conducted a field study with caches at public Wi-Fi hotspots in a field study. In addition, we present a queueing model for caches that we use to perform a mean-value analysis. We compare results from both methods in a performance analysis. Our results provide insights into difficulties of caching systems that are caused by an increase in the ratio of secured connections in the Internet.
  @inproceedings{info3-inproceedings-2017-8, abstract = {Caches are often employed to better manage the ever-growing amount of global Internet traffic. Particularly, reverse proxies are often used to free up congested peering links and reduce inter-domain traffic. In addition, caches place content close to the edge, leading to lower latency which can be beneficial for many applications. In an effort to bring content even closer to end devices, home routers and public access points are now in the spotlight as a novel location for caches. Compared to CDNs, a Wi-Fi router only offers scarce storage and processing capabilities, putting an increased emphasis on resource management. In addition, a large share of traffic is transmitted through secured connections preventing the use of forward caches and other middle boxes. This paper strives to analyze how effective caching can be in public Wi-Fi routers. For this purpose, we conducted a field study with caches at public Wi-Fi hotspots in a field study. In addition, we present a queueing model for caches that we use to perform a mean-value analysis. We compare results from both methods in a performance analysis. Our results provide insights into difficulties of caching systems that are caused by an increase in the ratio of secured connections in the Internet.}, address = {Paris, France}, author = {Moldovan, Christian and Burger, Valentin and Metzger, Florian and Surminski, Sebastian and Hoßfeld, Tobias}, booktitle = {IEEE ICC'17: Bridging People, Communities, and Cultures}, month = 5, title = {Viability of Wi-Fi Caches in an Era of HTTPS Prevalence}, year = 2017 }
• Wehner, N.: Simulative Evaluation of the QoE Fairness of HAS Adaptation Logics, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2017-10, author = {Wehner, Nikolas}, school = {University of Würzburg}, title = {Simulative Evaluation of the QoE Fairness of HAS Adaptation Logics}, year = 2017 }
• Tönsing, L.: Semi-automated Generation of Image Annotations using Crowdsourcing and Tools for automated Translation, (2017).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2017-1, author = {Tönsing, Lukas}, month = 3, school = {University of Wuerzburg}, title = {Semi-automated Generation of Image Annotations using Crowdsourcing and Tools for automated Translation}, year = 2017 }
• Borchert, K.: Unemployment and Online Labor. , Workshop on Flexible Work in the Digital Age, ZEW Mannheim, Germany (2017).
  [ BibTeX ]
   
  @presentation{info3-presentation-2017-1, address = {Workshop on Flexible Work in the Digital Age, ZEW Mannheim, Germany}, author = {Borchert, Kathrin}, month = 3, title = {Unemployment and Online Labor}, year = 2017 }
• Roth, D., Lugrin, J.-L., Latoschik, M.E., Huber, S.: Alpha IVBO - Construction of a Scale to Measure the Illusion of Virtual Body Ownership. Proceedings of the 35th Annual ACM Conference on Human Factors in Computing Systems (2017).
  [ BibTeX ]
   
  @inproceedings{roth2017alpha, author = {Roth, Daniel and Lugrin, Jean-Luc and Latoschik, Marc Erich and Huber, Stephan}, booktitle = {Proceedings of the 35th Annual ACM Conference on Human Factors in Computing Systems}, title = {Alpha IVBO - Construction of a Scale to Measure the Illusion of Virtual Body Ownership}, year = 2017 }
• Bruschke, J., Niebling, F., Maiwald, F., Friedrichs, K., Wacker, M., Latoschik, M.E.: Towards Browsing Repositories of Spatially Oriented Historic Photographic Images in 3D Web Environments. Proceedings of Web3D ’17, Brisbane, QLD, Australia (2017).
  [ Abstract ] [ BibTeX ]
   
  Archives and museums store vast collections of historical images of urban areas and make them publicly available through online platforms. Many of these images, often containing historic buildings and landscapes, can be oriented spatially using automatic methods such as structure from motion (SfM). Providing spatially and temporally oriented images of urban architecture, in combination with advanced searching and 2D/3D exploration techniques, offers new potentials in supporting historians in their research. We are developing a 3D web environment usable to historians to spatially search online media repositories containing historic photographic images. We combine 3D models of historic buildings with spatially oriented images, replacing text-based searching through meta-data with spatial and temporal browsing with respect to given focus points in historic city models.
  @inproceedings{bruschke2017towards, abstract = {Archives and museums store vast collections of historical images of urban areas and make them publicly available through online platforms. Many of these images, often containing historic buildings and landscapes, can be oriented spatially using automatic methods such as structure from motion (SfM). Providing spatially and temporally oriented images of urban architecture, in combination with advanced searching and 2D/3D exploration techniques, offers new potentials in supporting historians in their research. We are developing a 3D web environment usable to historians to spatially search online media repositories containing historic photographic images. We combine 3D models of historic buildings with spatially oriented images, replacing text-based searching through meta-data with spatial and temporal browsing with respect to given focus points in historic city models.}, author = {Bruschke, Jonas and Niebling, Florian and Maiwald, Ferdinand and Friedrichs, Kristina and Wacker, Markus and Latoschik, Marc Erich}, booktitle = {Proceedings of Web3D ’17, Brisbane, QLD, Australia}, month = {June 05-07}, title = {Towards Browsing Repositories of Spatially Oriented Historic Photographic Images in 3D Web Environments}, year = 2017 }
• Zinner, T., Geissler, S., Lange, S., Gebert, S., Seufert, M., Tran-Gia, P.: A Discrete-Time Model for Optimizing the Processing Time of Virtualized Network Functions. Computer Networks. 125, 4-14 (2017).
  [ Abstract ] [ BibTeX ]
   
  The softwarization of networks promises cost savings and better scalability of network functions by moving functionality from specialized devices into commercial off-the-shelf hardware. Generalized computing hardware offers many degrees of adjustment and tuning, which can affect performance and resource utilization. One of these adjustments are interrupt moderation techniques implemented by modern network interface cards and operating systems. Using these, an administrator can optimize either for low latencies or low CPU overhead for processing of network traffic. In this work, an analytical model that allows the computation of relevant performance metrics like packet processing time and packet loss for generic virtualized network functions running on commodity hardware is presented. Based on this model, impact factors like average packet interarrival time, interarrival time distribution, and duration of the interrupt aggregation interval are studied. Furthermore, we significantly improve the computational tractability of this discrete-time model by proving and leveraging a property regarding its limit behavior. We also demonstrate that using this property does not affect the accuracy of the model in the context of realistic parameter combinations. Finally, the improved runtime for numerical evaluations allows administrators to dynamically adapt their interrupt mitigation settings to changing network conditions by recalculating optimal parameters.
  @article{info3-article-2017-1, abstract = {The softwarization of networks promises cost savings and better scalability of network functions by moving functionality from specialized devices into commercial off-the-shelf hardware. Generalized computing hardware offers many degrees of adjustment and tuning, which can affect performance and resource utilization. One of these adjustments are interrupt moderation techniques implemented by modern network interface cards and operating systems. Using these, an administrator can optimize either for low latencies or low CPU overhead for processing of network traffic. In this work, an analytical model that allows the computation of relevant performance metrics like packet processing time and packet loss for generic virtualized network functions running on commodity hardware is presented. Based on this model, impact factors like average packet interarrival time, interarrival time distribution, and duration of the interrupt aggregation interval are studied. Furthermore, we significantly improve the computational tractability of this discrete-time model by proving and leveraging a property regarding its limit behavior. We also demonstrate that using this property does not affect the accuracy of the model in the context of realistic parameter combinations. Finally, the improved runtime for numerical evaluations allows administrators to dynamically adapt their interrupt mitigation settings to changing network conditions by recalculating optimal parameters.}, author = {Zinner, Thomas and Geissler, Stefan and Lange, Stanislav and Gebert, Steffen and Seufert, Michael and Tran-Gia, Phuoc}, journal = {Computer Networks}, pages = {4-14}, title = {A Discrete-Time Model for Optimizing the Processing Time of Virtualized Network Functions}, volume = 125, year = 2017 }
• Cofano, G., De Cicco, L., Zinner, T., Nguyen-Ngoc, A., Tran-Gia, P., Mascolo, S.: Design and Performance Evaluation of Network-assisted Control Strategies for HTTP Adaptive Streaming. ACM Transactions on Multimedia Computing, Communications, and Applications. (2017).
  [ BibTeX ]
   
  @article{info3-article-2017-2, author = {Cofano, Giuseppe and De Cicco, Luca and Zinner, Thomas and Nguyen-Ngoc, Anh and Tran-Gia, Phuoc and Mascolo, Saverio}, journal = {ACM Transactions on Multimedia Computing, Communications, and Applications}, title = {Design and Performance Evaluation of Network-assisted Control Strategies for HTTP Adaptive Streaming}, year = 2017 }
• Seufert, M., Wehner, N., Wamser, F., Casas, P., D'Alconzo, A., Tran-Gia, P.: Unsupervised QoE Field Study for Mobile YouTube Video Streaming with YoMoApp. 9th International Conference on Quality of Multimedia Experience (QoMEX). , Erfurt, Germany (2017).
  [ Abstract ] [ BibTeX ]
   
  YoMoApp (YouTube Monitoring App) is an Android app to monitor mobile YouTube video streaming on both application- and network-layer. Additionally, it allows to collect subjective Quality of Experience (QoE) feedback of end users. During the development of the app, the stable versions of YoMoApp were already available in the Google Play Store, and the app was downloaded, installed, and used on many devices to monitor streaming sessions. As the app was not advertised in special campaigns or used for dedicated QoE studies, the monitored streaming sessions of this period compose the data set of a large unsupervised field study. The collected data set is evaluated to characterize current mobile YouTube streaming on both application and network layers. Furthermore, the problems and methodology to obtain QoE results from such unsupervised field study are discussed together with the actual QoE results. Correlations between QoE factors are investigated, and the QoE of clusters of similar streaming sessions is analyzed.
  @inproceedings{info3-inproceedings-2017-9, abstract = {YoMoApp (YouTube Monitoring App) is an Android app to monitor mobile YouTube video streaming on both application- and network-layer. Additionally, it allows to collect subjective Quality of Experience (QoE) feedback of end users. During the development of the app, the stable versions of YoMoApp were already available in the Google Play Store, and the app was downloaded, installed, and used on many devices to monitor streaming sessions. As the app was not advertised in special campaigns or used for dedicated QoE studies, the monitored streaming sessions of this period compose the data set of a large unsupervised field study. The collected data set is evaluated to characterize current mobile YouTube streaming on both application and network layers. Furthermore, the problems and methodology to obtain QoE results from such unsupervised field study are discussed together with the actual QoE results. Correlations between QoE factors are investigated, and the QoE of clusters of similar streaming sessions is analyzed.}, address = {Erfurt, Germany}, author = {Seufert, Michael and Wehner, Nikolas and Wamser, Florian and Casas, Pedro and D'Alconzo, Alessandro and Tran-Gia, Phuoc}, booktitle = {9th International Conference on Quality of Multimedia Experience (QoMEX)}, month = 5, title = {Unsupervised QoE Field Study for Mobile YouTube Video Streaming with YoMoApp}, year = 2017 }
• Casas, P., D'Alconzo, A., Wamser, F., Seufert, M., Gardlo, B., Schwind, A., Tran-Gia, P., Schatz, R.: Predicting QoE in Cellular Networks using Machine Learning and in-Smartphone Measurements. 9th International Conference on Quality of Multimedia Experience (QoMEX). , Erfurt, Germany (2017).
  [ Abstract ] [ BibTeX ]
   
  Monitoring the Quality of Experience (QoE) undergone by cellular network customers has become paramount for cellular ISPs, who need to ensure high quality levels to limit customer churn due to quality dissatisfaction. This paper tackles the problem of QoE monitoring, assessment and prediction in cellular networks, relying on end-user device (i.e., smartphone) QoS passive traffic measurements and QoE crowdsourced feedback. We conceive different QoE assessment models based on supervised machine learning techniques, which are capable to predict the QoE experienced by the end user of popular smartphone apps (e.g., YouTube and Facebook), using as input the passive in-device measurements. Using a rich QoE dataset derived from field trials in operational cellular networks, we benchmark the performance of multiple machine learning based predictors, and construct a decision-tree based model which is capable to predict the per-user overall experience and service acceptability with a success rate of 91% and 98% respectively. To the best of our knowledge, this is the first paper using end-user, in-device passive measurements and machine learning models to predict the QoE of smartphone users in operational cellular networks.
  @inproceedings{info3-inproceedings-2017-10, abstract = {Monitoring the Quality of Experience (QoE) undergone by cellular network customers has become paramount for cellular ISPs, who need to ensure high quality levels to limit customer churn due to quality dissatisfaction. This paper tackles the problem of QoE monitoring, assessment and prediction in cellular networks, relying on end-user device (i.e., smartphone) QoS passive traffic measurements and QoE crowdsourced feedback. We conceive different QoE assessment models based on supervised machine learning techniques, which are capable to predict the QoE experienced by the end user of popular smartphone apps (e.g., YouTube and Facebook), using as input the passive in-device measurements. Using a rich QoE dataset derived from field trials in operational cellular networks, we benchmark the performance of multiple machine learning based predictors, and construct a decision-tree based model which is capable to predict the per-user overall experience and service acceptability with a success rate of 91% and 98% respectively. To the best of our knowledge, this is the first paper using end-user, in-device passive measurements and machine learning models to predict the QoE of smartphone users in operational cellular networks.}, address = {Erfurt, Germany}, author = {Casas, Pedro and D'Alconzo, Alessandro and Wamser, Florian and Seufert, Michael and Gardlo, Bruno and Schwind, Anika and Tran-Gia, Phuoc and Schatz, Raimund}, booktitle = {9th International Conference on Quality of Multimedia Experience (QoMEX)}, month = 5, title = {Predicting QoE in Cellular Networks using Machine Learning and in-Smartphone Measurements}, year = 2017 }
• Seufert, M., Zach, O., Slanina, M., Tran-Gia, P.: Unperturbed Video Streaming QoE Under Web Page Related Context Factors. 9th International Conference on Quality of Multimedia Experience (QoMEX). , Erfurt, Germany (2017).
  [ Abstract ] [ BibTeX ]
   
  Quality of Experience (QoE) of Internet services is affected by human, system, and context influence factors. While most QoE studies so far are focused on system factors only, this work will assess the impact of context factors of video streaming on QoE. As video streaming is mostly consumed from web pages, such as video portals, the investigated test conditions are applied to the web page, which embeds the video player. Therefore, the study of context factors is implicitly conducted within a crowdsourced QoE study. The test conditions considered different page load times, poster image qualities, and displayed advertisements on the web page, which are typical context factors when consuming a video streaming service. The results of the study show that the modification of the context factors on the streaming web page leaves the users' QoE rating unperturbed, which suggests that the investigated context factors have a negligible impact on video streaming QoE, or that the rating task of the subjective QoE study superimposed the context factors.
  @inproceedings{info3-inproceedings-2017-11, abstract = {Quality of Experience (QoE) of Internet services is affected by human, system, and context influence factors. While most QoE studies so far are focused on system factors only, this work will assess the impact of context factors of video streaming on QoE. As video streaming is mostly consumed from web pages, such as video portals, the investigated test conditions are applied to the web page, which embeds the video player. Therefore, the study of context factors is implicitly conducted within a crowdsourced QoE study. The test conditions considered different page load times, poster image qualities, and displayed advertisements on the web page, which are typical context factors when consuming a video streaming service. The results of the study show that the modification of the context factors on the streaming web page leaves the users' QoE rating unperturbed, which suggests that the investigated context factors have a negligible impact on video streaming QoE, or that the rating task of the subjective QoE study superimposed the context factors.}, address = {Erfurt, Germany}, author = {Seufert, Michael and Zach, Ondrej and Slanina, Martin and Tran-Gia, Phuoc}, booktitle = {9th International Conference on Quality of Multimedia Experience (QoMEX)}, month = 5, title = {Unperturbed Video Streaming QoE Under Web Page Related Context Factors}, year = 2017 }
• Supervisor: Grigorjew, A.: Development and Evaluation of Algorithms for Online Distributed Virtual Network Function Deployment and Consolidation, (2017).
  [ Abstract ] [ BibTeX ]
   
  Contact: Alexej Grigorjew <alexej.grigorjew@informatik.uni-wuerzburg.de> Network Function Virtualization (NFV) is an emerging trend in the field of network design and operation. Traditionally, various network functions (such as Firewalls, Intrusion Detection Systems, Deep Packet Inspection, ...) are applied to flows in the network, and currently implemented by specialized hardware middleboxes. In the context of NFV, these network functions are now implemented in software and deployed on virtual machines running on commodity servers (→ Virtual Network Functions, VNFs). This enables far greater flexibility and, consequently, comes with new optimization problems. One important part of these problems is to decide how many of these VNF instances are needed, and where they should be placed. Together with various constraints (bandwidth, CPU capacities, ...) and objectives (minimize costs, delays, ...), these questions form an NP-hard optimization problem. In this particular work, the online version of this problem shall be investigated, i.e., new instances are created and removed from the network during its operation, as new traffic demands arrive or leave the network. The aim is to design algorithms that are able to make these decisions locally (i.e., no central decision unit) and to evaluate their performance with respect to chosen objectives, for example by means of a simulation. The student shall (among other things) ... - formalize the problem and its context, - outline its relation to existing, related approaches, - develop optimization algorithms for VNF placement and removal, - define appropriate measures for the quality of attained placements, - evaluate the placement quality by means of these measures (→ discrete event simulation), - and interpret attained results. For further information, feel free to contact us in person or send an email.
  @mastersthesis{info3-master-2017-9, abstract = {Contact: Alexej Grigorjew <alexej.grigorjew@informatik.uni-wuerzburg.de> Network Function Virtualization (NFV) is an emerging trend in the field of network design and operation. Traditionally, various network functions (such as Firewalls, Intrusion Detection Systems, Deep Packet Inspection, ...) are applied to flows in the network, and currently implemented by specialized hardware middleboxes. In the context of NFV, these network functions are now implemented in software and deployed on virtual machines running on commodity servers (→ Virtual Network Functions, VNFs). This enables far greater flexibility and, consequently, comes with new optimization problems. One important part of these problems is to decide how many of these VNF instances are needed, and where they should be placed. Together with various constraints (bandwidth, CPU capacities, ...) and objectives (minimize costs, delays, ...), these questions form an NP-hard optimization problem. In this particular work, the online version of this problem shall be investigated, i.e., new instances are created and removed from the network during its operation, as new traffic demands arrive or leave the network. The aim is to design algorithms that are able to make these decisions locally (i.e., no central decision unit) and to evaluate their performance with respect to chosen objectives, for example by means of a simulation. The student shall (among other things) ... - formalize the problem and its context, - outline its relation to existing, related approaches, - develop optimization algorithms for VNF placement and removal, - define appropriate measures for the quality of attained placements, - evaluate the placement quality by means of these measures (→ discrete event simulation), - and interpret attained results. For further information, feel free to contact us in person or send an email.}, author = {Supervisor: Grigorjew, Alexej}, school = {University of Würzburg}, title = {Development and Evaluation of Algorithms for Online Distributed Virtual Network Function Deployment and Consolidation}, year = 2017 }
• Bott, L.: Implementing Backup Paths and Recovery Strategies in an SDN controlled by ONOS, (2017).
  [ Abstract ] [ BibTeX ]
   
  As the migration towards SDN is in progress, the satisfaction of carrier-grade requirements (fast failure detection, fast reaction, high availability throughout the year) becomes more and more important. The SDN controller ONOS already provides promising mechanisms and tools, but lacks certain capabilities. The task of the project is to enhance ONOS capabilities by implementing the provisioning of backup paths and recovery strategies. <christopher.metter@informatik.uni-wuerzburg.de>
  @mastersthesis{info3-praktikum-2017-6, abstract = {As the migration towards SDN is in progress, the satisfaction of carrier-grade requirements (fast failure detection, fast reaction, high availability throughout the year) becomes more and more important. The SDN controller ONOS already provides promising mechanisms and tools, but lacks certain capabilities. The task of the project is to enhance ONOS capabilities by implementing the provisioning of backup paths and recovery strategies. <christopher.metter@informatik.uni-wuerzburg.de>}, author = {Bott, Lukas}, school = {University of Würzburg}, title = {Implementing Backup Paths and Recovery Strategies in an SDN controlled by ONOS}, year = 2017 }
• Borchert, K., Hirth, M., Zinner, T., Göritz, A.: Designing a Survey Tool for Monitoring Enterprise QoE. ACM SIGCOMM Workshop on QoE-based Analysis and Management of Data Communication Networks (Internet-QoE). , Los Angeles, CA, USA (2017).
  [ Abstract ] [ BibTeX ]
   
  Enterprise applications like SAP are part of the day-to-day work of a large number of employees. Similar to many modern applications, enterprise applications are often implemented in a distributed fashion and consequently suffer from network degradations resulting in impairments like increased loading delays. While the influence of these impairments on the perceived quality of users is well researched for consumer applications and network services, the impact of these impairments in a business environment is still unclear. To address this gap we develop a non-intrusive software tool for continuously collecting subjective ratings on the performance of an enterprise application from a large crowd of employees. Based on the feedback from a company and results from two initial field studies we discuss the specific challenges when assessing the perceived quality of employees during regular working hours and point our further research directions.
  @inproceedings{info3-inproceedings-2017-13, abstract = {Enterprise applications like SAP are part of the day-to-day work of a large number of employees. Similar to many modern applications, enterprise applications are often implemented in a distributed fashion and consequently suffer from network degradations resulting in impairments like increased loading delays. While the influence of these impairments on the perceived quality of users is well researched for consumer applications and network services, the impact of these impairments in a business environment is still unclear. To address this gap we develop a non-intrusive software tool for continuously collecting subjective ratings on the performance of an enterprise application from a large crowd of employees. Based on the feedback from a company and results from two initial field studies we discuss the specific challenges when assessing the perceived quality of employees during regular working hours and point our further research directions.}, address = {Los Angeles, CA, USA}, author = {Borchert, Kathrin and Hirth, Matthias and Zinner, Thomas and Göritz, Anja}, booktitle = {ACM SIGCOMM Workshop on QoE-based Analysis and Management of Data Communication Networks (Internet-QoE)}, month = 8, title = {Designing a Survey Tool for Monitoring Enterprise QoE}, year = 2017 }
• Gray, N.: Evaluation of Offloading Firewall Rules with P4, (2017).
  [ Abstract ] [ BibTeX ]
   
  Contact: nicholas.gray@informatik.uni-wuerzburg.de Firewalls are classical network middle boxes, which are physically implemented within the data path. Following this design pattern causes the network to become inflexible and harder to scale as additional hardware devices have to be deployed whenever the limits of the current configuration are reached, resulting in a high maintenance and requisition cost. Network Function Virtualization (NFV) is a novel paradigm aiming to mitigate these drawbacks by shifting the function of hardware middle boxes to software programs run on Commodity of the Shelf servers. While increasing the network flexibility, it also imposes additional delays on the data path as the complete networking and software stack has to be traversed for each packet. P4 allows the execution and packet matching process on inexpensive, programmable networking cards at line rate. Goal of the thesis is the implementation and evaluation of a distributed stateful firewall based on P4.
  @mastersthesis{info3-master-2017-7, abstract = {Contact: nicholas.gray@informatik.uni-wuerzburg.de Firewalls are classical network middle boxes, which are physically implemented within the data path. Following this design pattern causes the network to become inflexible and harder to scale as additional hardware devices have to be deployed whenever the limits of the current configuration are reached, resulting in a high maintenance and requisition cost. Network Function Virtualization (NFV) is a novel paradigm aiming to mitigate these drawbacks by shifting the function of hardware middle boxes to software programs run on Commodity of the Shelf servers. While increasing the network flexibility, it also imposes additional delays on the data path as the complete networking and software stack has to be traversed for each packet. P4 allows the execution and packet matching process on inexpensive, programmable networking cards at line rate. Goal of the thesis is the implementation and evaluation of a distributed stateful firewall based on P4.}, author = {Gray, Nicholas}, school = {University of Wuerzburg}, title = {Evaluation of Offloading Firewall Rules with P4}, year = 2017 }
• Sträßer, M.: SDN-based Elephant Detection, (2017).
  [ Abstract ] [ BibTeX ]
   
  ZOOM is an SDN based approach for elephant detection in SDN enabled networks. The idea is to split the IP address space into sections that are iteratively refined until only the largest flows remain. These are then returned as elephant flows. A proof-of-concept implementation and basic evaluation has already been performed in the paper emphZOOM: Lightweight SDN-based Elephant Detection.
  @mastersthesis{info3-master-2016-6, abstract = {ZOOM is an SDN based approach for elephant detection in SDN enabled networks. The idea is to split the IP address space into sections that are iteratively refined until only the largest flows remain. These are then returned as elephant flows. A proof-of-concept implementation and basic evaluation has already been performed in the paper emphZOOM: Lightweight SDN-based Elephant Detection.}, author = {Sträßer, Martin}, school = {University of Würzburg}, title = {SDN-based Elephant Detection}, year = 2017 }
• Wamser, F., Höfner, S., Seufert, M., Tran-Gia, P.: Client-side Dynamic Server Selection for MPEG DASH Video Streaming. ACM SIGCOMM Workshop on QoE-based Analysis and Management of Data Communication Networks (Internet-QoE). , Los Angeles, CA, USA (2017).
  [ Abstract ] [ BibTeX ]
   
  In HTTP adaptive streaming (HAS), such as MPEG DASH, the video is split into chunks and is available in different quality levels. If the video chunks are stored or cached on different servers to deal with the high load in the network and the Quality of Experience (QoE) requirements of the users, the problem of content selection arises. In this paper, we evaluate client-side algorithms for dynamically selecting an appropriate content server during DASH video streaming. We present three algorithms with which the DASH client itself can determine the most appropriate server based on client-specific metrics, like actual latency or bandwidth to the content servers. We evaluate and discuss the proposed algorithms with respect to the resulting DASH streaming behavior in terms of buffer levels and quality level selection.
  @inproceedings{info3-article-2017-3, abstract = {In HTTP adaptive streaming (HAS), such as MPEG DASH, the video is split into chunks and is available in different quality levels. If the video chunks are stored or cached on different servers to deal with the high load in the network and the Quality of Experience (QoE) requirements of the users, the problem of content selection arises. In this paper, we evaluate client-side algorithms for dynamically selecting an appropriate content server during DASH video streaming. We present three algorithms with which the DASH client itself can determine the most appropriate server based on client-specific metrics, like actual latency or bandwidth to the content servers. We evaluate and discuss the proposed algorithms with respect to the resulting DASH streaming behavior in terms of buffer levels and quality level selection.}, address = {Los Angeles, CA, USA}, author = {Wamser, Florian and Höfner, Steffen and Seufert, Michael and Tran-Gia, Phuoc}, booktitle = {ACM SIGCOMM Workshop on QoE-based Analysis and Management of Data Communication Networks (Internet-QoE)}, month = 8, title = {Client-side Dynamic Server Selection for MPEG DASH Video Streaming}, year = 2017 }
• Borchert, K., Hirth, M., Zinner, T., Göritz, A.: Collecting Subjective Ratings in Enterprise Environments. 9th International Conference on Quality of Multimedia Experience (QoMEX). , Erfurt, Germany (2017).
  [ BibTeX ]
   
  @inproceedings{info3-inproceedings-2017-14, address = {Erfurt, Germany}, author = {Borchert, Kathrin and Hirth, Matthias and Zinner, Thomas and Göritz, Anja}, booktitle = {9th International Conference on Quality of Multimedia Experience (QoMEX)}, month = 5, title = {Collecting Subjective Ratings in Enterprise Environments}, year = 2017 }
• Supervisor: Schwind, A.: Einfluss von persönlicher Bekanntheit und Popularität eines Videos auf die QoE, (2017).
  [ Abstract ] [ BibTeX ]
   
  Contact: anika.schwind@informatik.uni-wuerzburg.de
  @mastersthesis{info3-praktikum-2017-11, abstract = {Contact: anika.schwind@informatik.uni-wuerzburg.de}, author = {Supervisor: Schwind, Anika}, school = {University of Wuerzburg}, title = {Einfluss von persönlicher Bekanntheit und Popularität eines Videos auf die QoE}, year = 2017 }
• Schwind, A., Seufert, M., Alay, Ö., Casas, P., Tran-Gia, P., Wamser, F.: Concept and Implementation of Video QoE Measurements in a Mobile Broadband Testbed. IEEE/IFIP Workshop on Mobile Network Measurement (MNM’17). , Dublin, Ireland (2017).
  [ Abstract ] [ BibTeX ]
   
  The MONROE testbed enables the objective performance assessment of MBB networks from the end-user perspective, using highly distributed measurements from fixed and mobile nodes. To quantify the performance of MBB networks for popular Internet services from a user-centric perspective, dedicated tools are needed. In this paper we extend the MONROE testbed to the Quality of Experience (QoE) domain, presenting the design and implementation of a QoE-capable measurement tool for YouTube video streaming. The measurement concept is based on emulating a virtual end-user device requesting video streams, which are then monitored at the network and application layers, on the basis of QoE-relevant features. The initial measurements conducted in the MONROE testbed and reported in this paper demonstrate the applicability of the implemented measurement concept.
  @inproceedings{info3-inproceedings-2017-15, abstract = {The MONROE testbed enables the objective performance assessment of MBB networks from the end-user perspective, using highly distributed measurements from fixed and mobile nodes. To quantify the performance of MBB networks for popular Internet services from a user-centric perspective, dedicated tools are needed. In this paper we extend the MONROE testbed to the Quality of Experience (QoE) domain, presenting the design and implementation of a QoE-capable measurement tool for YouTube video streaming. The measurement concept is based on emulating a virtual end-user device requesting video streams, which are then monitored at the network and application layers, on the basis of QoE-relevant features. The initial measurements conducted in the MONROE testbed and reported in this paper demonstrate the applicability of the implemented measurement concept.}, address = {Dublin, Ireland}, author = {Schwind, Anika and Seufert, Michael and Alay, Özgü and Casas, Pedro and Tran-Gia, Phuoc and Wamser, Florian}, booktitle = {IEEE/IFIP Workshop on Mobile Network Measurement (MNM’17)}, month = 6, title = {Concept and Implementation of Video QoE Measurements in a Mobile Broadband Testbed}, year = 2017 }
• Loh, F.: Determination of Traffic Patterns by a Remote Controllable Drone, (2017).
  [ Abstract ] [ BibTeX ]
   
  Durch die steigende Anzahl an Endgeräten im Netzwerk und den damit verbundenen Anstieg an Datenverkehr ist es für den Provider wichtig, die erzeugte Menge an Datenverkehr genau zu kennen. Dies stellt sich durch viele neue Geräte mit neuen Verkehrsmustern jedoch als schwierig heraus, weshalb detaillierte Verkehrsmodelle für jedes Gerät erstellt werden müssen. Auf der anderen Seite profitiert auch der Nutzer von der genauen Verkehrsanalyse. Störungen in von ihm genutzen Services werden schneller erkannt und behoben. In der hier vorgestellten Arbeit soll diese Verkehrsanalyse anhand einer vom Nutzer ferngesteuerten Drohne durchgeführt werden: Ziel der Arbeit ist es mit Hilfe einer am Lehrstuhl vorhandenen Drohne Datenverkehrsmessungen durchzuführen und zu evaluieren. Es soll herausgefunden werden, wie sich die Distanz zum Nutzer oder Hindernisse zwischen dem Nutzer und der Drohne auf den Datendurchsatz beispielsweise bei einer WiFi oder Bluetooth Verbindung auswirkt. Abschließend sollen die gewonnenen Ergebnisse mit Hilfe von vorhandenen Verkehrsmustern verglichen werden und Gemeinsamkeiten sowie Unterschiede herausgefunden und analysiert werden.
  @mastersthesis{info3-bachelor-2017-21, abstract = {Durch die steigende Anzahl an Endgeräten im Netzwerk und den damit verbundenen Anstieg an Datenverkehr ist es für den Provider wichtig, die erzeugte Menge an Datenverkehr genau zu kennen. Dies stellt sich durch viele neue Geräte mit neuen Verkehrsmustern jedoch als schwierig heraus, weshalb detaillierte Verkehrsmodelle für jedes Gerät erstellt werden müssen. Auf der anderen Seite profitiert auch der Nutzer von der genauen Verkehrsanalyse. Störungen in von ihm genutzen Services werden schneller erkannt und behoben. In der hier vorgestellten Arbeit soll diese Verkehrsanalyse anhand einer vom Nutzer ferngesteuerten Drohne durchgeführt werden: Ziel der Arbeit ist es mit Hilfe einer am Lehrstuhl vorhandenen Drohne Datenverkehrsmessungen durchzuführen und zu evaluieren. Es soll herausgefunden werden, wie sich die Distanz zum Nutzer oder Hindernisse zwischen dem Nutzer und der Drohne auf den Datendurchsatz beispielsweise bei einer WiFi oder Bluetooth Verbindung auswirkt. Abschließend sollen die gewonnenen Ergebnisse mit Hilfe von vorhandenen Verkehrsmustern verglichen werden und Gemeinsamkeiten sowie Unterschiede herausgefunden und analysiert werden.}, author = {Loh, Frank}, school = {University of Würzburg}, title = {Determination of Traffic Patterns by a Remote Controllable Drone}, year = 2017 }
• Burger, V., Seufert, M., Zinner, T., Tran-Gia, P.: An Approximation of the Backhaul Bandwidth Aggregation Potential Using a Partial Sharing Scheme. 15th IFIP/IEEE International Symposium on Integrated Network Management (IM). , Lisbon, Portugal (2017).
  [ Abstract ] [ BibTeX ]
   
  To cope with the increasing demands of mobile devices and the limited capacity of cellular networks, mobile connections are offloaded to WiFi. The access capacity is further increased by aggregating backhaul bandwidth of WiFi access links. To analyze the performance of aggregated access links we develop a model for two and more cooperating systems sharing capacities using an offloading scheme. The state probabilities of the different cooperating systems in the analytic model are determined by a fixed point iterative procedure. By investigating an inner and outer composite system we are able to analyze the system in imbalanced load conditions where the system reaches its full potential utilizing spare bandwidth. To evaluate the robustness of the system against users that try to exploit the system, the bandwidth received by prioritized users is quantified.
  @inproceedings{info3-inproceedings-2017-1, abstract = {To cope with the increasing demands of mobile devices and the limited capacity of cellular networks, mobile connections are offloaded to WiFi. The access capacity is further increased by aggregating backhaul bandwidth of WiFi access links. To analyze the performance of aggregated access links we develop a model for two and more cooperating systems sharing capacities using an offloading scheme. The state probabilities of the different cooperating systems in the analytic model are determined by a fixed point iterative procedure. By investigating an inner and outer composite system we are able to analyze the system in imbalanced load conditions where the system reaches its full potential utilizing spare bandwidth. To evaluate the robustness of the system against users that try to exploit the system, the bandwidth received by prioritized users is quantified.}, address = {Lisbon, Portugal}, author = {Burger, Valentin and Seufert, Michael and Zinner, Thomas and Tran-Gia, Phuoc}, booktitle = {15th IFIP/IEEE International Symposium on Integrated Network Management (IM)}, month = 5, title = {An Approximation of the Backhaul Bandwidth Aggregation Potential Using a Partial Sharing Scheme}, year = 2017 }
• Chimani, M., Felsner, S., Kobourov, S., Ueckerdt, T., Valtr, P., Wolff, A.: On the Maximum Crossing Number. In: Brankovic, L., Ryan, J., und Smith, B. (hrsg.) Proc. 28th Int. Workshop Combin. Algorithms (IWOCA'17). Springer-Verlag (2017).
  [ BibTeX ]
   
  @inproceedings{cfkuvw-mcn-IWOCA17, author = {Chimani, Markus and Felsner, Stefan and Kobourov, Stephen and Ueckerdt, Torsten and Valtr, Pavel and Wolff, Alexander}, booktitle = {Proc. 28th Int. Workshop Combin. Algorithms (IWOCA'17)}, editor = {Brankovic, Ljiljana and Ryan, Joe and Smith, Bill}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {On the Maximum Crossing Number}, year = 2017 }
• Chaplick, S., Fleszar, K., Lipp, F., Ravsky, A., Verbitsky, O., Wolff, A.: The Complexity of Drawing Graphs on Few Lines and Few Planes. In: Ellen, F., Kolokolova, A., und Sack, J.-R. (hrsg.) Proc. Algorithms Data Struct. Symp. (WADS'17). Springer-Verlag (2017).
  [ BibTeX ]
   
  @inproceedings{cflrvw-cdgfl-WADS17, author = {Chaplick, Steven and Fleszar, Krzysztof and Lipp, Fabian and Ravsky, Alexander and Verbitsky, Oleg and Wolff, Alexander}, booktitle = {Proc. Algorithms Data Struct. Symp. (WADS'17)}, editor = {Ellen, Faith and Kolokolova, Antonina and Sack, Jörg-Rüdiger}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {The Complexity of Drawing Graphs on Few Lines and Few Planes}, year = 2017 }
• Lorenz, C., Hock, D., Scherer, J., Durner, R., Kellerer, W., Gebert, S., Gray, N., Zinner, T., Tran-Gia, P.: An SDN/NFV-enabled Enterprise Network Architecture Offering Fine-Grained Security Policy Enforcement. IEEE Communications Magazine. 55, 217 - 223 (2017).
  [ Abstract ] [ BibTeX ]
   
  In recent years, the number of attacks and threat vectors against enterprise networks have been constantly increasing in numbers and variety. In addition, new challenges arise not only to the level of provided security, but also to the scalability and manageability of the deployed countermeasures such as firewalls and intrusion detection systems. Despite these attacks, the main security systems, e.g., network firewalls, have remained rather unchanged. Due to the tight integration into the physical network’s infrastructure, a dynamic resource allocation to adapt the security measures to the current network conditions is a difficult undertaking. Therefore, in this work, we analyze and compare different architectural design patterns for the integration of SDN/NFV-based security solutions into enterprise networks.
  @article{info3-article-2016-9, abstract = {In recent years, the number of attacks and threat vectors against enterprise networks have been constantly increasing in numbers and variety. In addition, new challenges arise not only to the level of provided security, but also to the scalability and manageability of the deployed countermeasures such as firewalls and intrusion detection systems. Despite these attacks, the main security systems, e.g., network firewalls, have remained rather unchanged. Due to the tight integration into the physical network’s infrastructure, a dynamic resource allocation to adapt the security measures to the current network conditions is a difficult undertaking. Therefore, in this work, we analyze and compare different architectural design patterns for the integration of SDN/NFV-based security solutions into enterprise networks.}, author = {Lorenz, Claas and Hock, David and Scherer, Johann and Durner, Raphael and Kellerer, Wolfgang and Gebert, Steffen and Gray, Nicholas and Zinner, Thomas and Tran-Gia, Phuoc}, journal = {IEEE Communications Magazine}, month = 3, number = 3, pages = {217 - 223}, title = {An SDN/NFV-enabled Enterprise Network Architecture Offering Fine-Grained Security Policy Enforcement}, volume = 55, year = 2017 }
• Bekos, M.A., van Dijk, T.C., Fink, M., Kindermann, P., Kobourov, S., Pupyrev, S., Spoerhase, J., Wolff, A.: Improved Approximation Algorithms for Box Contact Representations. Algorithmica. 77, 902--920 (2017).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  We study the following geometric representation problem: Given a graph whose vertices correspond to axis-aligned rectangles with fixed dimensions, arrange the rectangles without overlaps in the plane such that two rectangles touch if the graph contains an edge between them. This problem is called Contact Representation of Word Networks (Crown) since it formalizes the geometric problem behind drawing word clouds in which semantically related words are close to each other. Crown is known to be NP-hard, and there are approximation algorithms for certain graph classes for the optimization version, Max-Crown, in which realizing each desired adjacency yields a certain profit. We present the first \($O(1)$\)-approximation algorithm for the general case, when the input is a complete weighted graph, and for the bipartite case. Since the subgraph of realized adjacencies is necessarily planar, we also consider several planar graph classes (namely stars, trees, outerplanar, and planar graphs), improving upon the known results. For some graph classes, we also describe improvements in the unweighted case, where each adjacency yields the same profit. Finally, we show that the problem is APX-complete on bipartite graphs of bounded maximum degree.
  @article{bdfkkpsw-iaabc-Algorithmica17, abstract = {We study the following geometric representation problem: Given a graph whose vertices correspond to axis-aligned rectangles with fixed dimensions, arrange the rectangles without overlaps in the plane such that two rectangles touch if the graph contains an edge between them. This problem is called Contact Representation of Word Networks (Crown) since it formalizes the geometric problem behind drawing word clouds in which semantically related words are close to each other. Crown is known to be NP-hard, and there are approximation algorithms for certain graph classes for the optimization version, Max-Crown, in which realizing each desired adjacency yields a certain profit. We present the first \($O(1)$\)-approximation algorithm for the general case, when the input is a complete weighted graph, and for the bipartite case. Since the subgraph of realized adjacencies is necessarily planar, we also consider several planar graph classes (namely stars, trees, outerplanar, and planar graphs), improving upon the known results. For some graph classes, we also describe improvements in the unweighted case, where each adjacency yields the same profit. Finally, we show that the problem is APX-complete on bipartite graphs of bounded maximum degree.}, author = {Bekos, Michael A. and van Dijk, Thomas C. and Fink, Martin and Kindermann, Philipp and Kobourov, Stephen and Pupyrev, Sergey and Spoerhase, Joachim and Wolff, Alexander}, journal = {Algorithmica}, number = 3, pages = {902--920}, title = {Improved Approximation Algorithms for Box Contact Representations}, volume = 77, year = 2017 }
• Seufert, M., Kamneng Kwam, B., Wamser, F., Tran-Gia, P.: EdgeNetworkCloudSim: Placement of Service Chains in Edge Clouds Using NetworkCloudSim. 1st IEEE International Workshop on Network Programmability - From the Data Center to the Ground (NetFoG). , Bologna, Italy (2017).
  [ Abstract ] [ BibTeX ]
   
  Edge cloud computing is a trending paradigm, which extends cloud computing by additionally utilizing computing resources at the network edge, e.g., at mobile base stations. Especially personalized services can be instantiated or migrated close to end users, which improves the latency and supports user mobility. However, the placement of the service chains is crucial for the performance of the services and the energy consumption of the edge cloud platform, and appropriate algorithms have to be designed. To support the simulative performance evaluation of such algorithms, EdgeNetworkCloudSim was developed. It is an extension of NetworkCloudSim, and allows to simulate and evaluate the orchestration and consolidation of service chains in an edge network cloud.
  @inproceedings{info3-inproceedings-2017-12, abstract = {Edge cloud computing is a trending paradigm, which extends cloud computing by additionally utilizing computing resources at the network edge, e.g., at mobile base stations. Especially personalized services can be instantiated or migrated close to end users, which improves the latency and supports user mobility. However, the placement of the service chains is crucial for the performance of the services and the energy consumption of the edge cloud platform, and appropriate algorithms have to be designed. To support the simulative performance evaluation of such algorithms, EdgeNetworkCloudSim was developed. It is an extension of NetworkCloudSim, and allows to simulate and evaluate the orchestration and consolidation of service chains in an edge network cloud.}, address = {Bologna, Italy}, author = {Seufert, Michael and Kamneng Kwam, Brice and Wamser, Florian and Tran-Gia, Phuoc}, booktitle = {1st IEEE International Workshop on Network Programmability - From the Data Center to the Ground (NetFoG)}, month = 7, title = {EdgeNetworkCloudSim: Placement of Service Chains in Edge Clouds Using NetworkCloudSim}, year = 2017 }
• Niebler, T., Becker, M., Pölitz, C., Hotho, A.: Learning Semantic Relatedness From Human Feedback Using Metric Learning, http://arxiv.org/abs/1705.07425, (2017).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  Assessing the degree of semantic relatedness between words is an important task with a variety of semantic applications, such as ontology learning for the Semantic Web, semantic search or query expansion. To accomplish this in an automated fashion, many relatedness measures have been proposed. However, most of these metrics only encode information contained in the underlying corpus and thus do not directly model human intuition. To solve this, we propose to utilize a metric learning approach to improve existing semantic relatedness measures by learning from additional information, such as explicit human feedback. For this, we argue to use word embeddings instead of traditional high-dimensional vector representations in order to leverage their semantic density and to reduce computational cost. We rigorously test our approach on several domains including tagging data as well as publicly available embeddings based on Wikipedia texts and navigation. Human feedback about semantic relatedness for learning and evaluation is extracted from publicly available datasets such as MEN or WS-353. We find that our method can significantly improve semantic relatedness measures by learning from additional information, such as explicit human feedback. For tagging data, we are the first to generate and study embeddings. Our results are of special interest for ontology and recommendation engineers, but also for any other researchers and practitioners of Semantic Web techniques.
  @misc{niebler2017learning, abstract = {Assessing the degree of semantic relatedness between words is an important task with a variety of semantic applications, such as ontology learning for the Semantic Web, semantic search or query expansion. To accomplish this in an automated fashion, many relatedness measures have been proposed. However, most of these metrics only encode information contained in the underlying corpus and thus do not directly model human intuition. To solve this, we propose to utilize a metric learning approach to improve existing semantic relatedness measures by learning from additional information, such as explicit human feedback. For this, we argue to use word embeddings instead of traditional high-dimensional vector representations in order to leverage their semantic density and to reduce computational cost. We rigorously test our approach on several domains including tagging data as well as publicly available embeddings based on Wikipedia texts and navigation. Human feedback about semantic relatedness for learning and evaluation is extracted from publicly available datasets such as MEN or WS-353. We find that our method can significantly improve semantic relatedness measures by learning from additional information, such as explicit human feedback. For tagging data, we are the first to generate and study embeddings. Our results are of special interest for ontology and recommendation engineers, but also for any other researchers and practitioners of Semantic Web techniques.}, author = {Niebler, Thomas and Becker, Martin and Pölitz, Christian and Hotho, Andreas}, note = {cite arxiv:1705.07425Comment: Under review at ISWC 2017}, title = {Learning Semantic Relatedness From Human Feedback Using Metric Learning}, year = 2017 }

2016 [ nach oben ]

• Burger, V., Zinner, T.: Performance Analysis of Hierarchical Caching Systems with Bandwidth Constraints. Proceedings of the International Telecommunication Networks and Applications Conference. , Dunedin, New Zealand (2016).
  [ Abstract ] [ BibTeX ]
   
  The vast majority of Internet traffic is carried by content delivery networks. A high potential to bring content even closer to consumers and to reduce energy cost is achieved by the nano data center (NaDa) concept that has been proposed in recent work. In this approach the capacity available on small devices such as home gateways is used to support content delivery in an hierarchical caching system. In this work, we present a method to determine the efficiency of hierarchical content delivery networks with limited bandwidth, such as in the NaDa approach, analytically. We analyze the Internet Census Dataset to assess the number of available devices on autonomous system level. We evaluate the potential of hierarchical cache networks with bandwidth constraints to assist content delivery and determine its limits.
  @inproceedings{info3-inproceedings-2016-22, abstract = {The vast majority of Internet traffic is carried by content delivery networks. A high potential to bring content even closer to consumers and to reduce energy cost is achieved by the nano data center (NaDa) concept that has been proposed in recent work. In this approach the capacity available on small devices such as home gateways is used to support content delivery in an hierarchical caching system. In this work, we present a method to determine the efficiency of hierarchical content delivery networks with limited bandwidth, such as in the NaDa approach, analytically. We analyze the Internet Census Dataset to assess the number of available devices on autonomous system level. We evaluate the potential of hierarchical cache networks with bandwidth constraints to assist content delivery and determine its limits.}, address = {Dunedin, New Zealand}, author = {Burger, Valentin and Zinner, Thomas}, booktitle = {Proceedings of the International Telecommunication Networks and Applications Conference}, month = 12, title = {Performance Analysis of Hierarchical Caching Systems with Bandwidth Constraints}, year = 2016 }
• Seufert, M., Hoßfeld, T., Schwind, A., Burger, V., Tran-Gia, P.: Group-based Communication in WhatsApp. 1st IFIP Internet of People Workshop (IoP). , Vienna, Austria (2016).
  [ Abstract ] [ BibTeX ]
   
  WhatsApp is a very popular mobile messaging application, which dominates today’s mobile communication. Especially the feature of group chats contributes to its success and changes the way people communicate. The group-based communication paradigm is investigated in this work, particularly focusing on the usage of WhatsApp, communication in group chats, and implications on mobile network traffic.
  @inproceedings{info3-inproceedings-2016-1, abstract = {WhatsApp is a very popular mobile messaging application, which dominates today’s mobile communication. Especially the feature of group chats contributes to its success and changes the way people communicate. The group-based communication paradigm is investigated in this work, particularly focusing on the usage of WhatsApp, communication in group chats, and implications on mobile network traffic.}, address = {Vienna, Austria}, author = {Seufert, Michael and Hoßfeld, Tobias and Schwind, Anika and Burger, Valentin and Tran-Gia, Phuoc}, booktitle = {1st IFIP Internet of People Workshop (IoP)}, month = 5, title = {Group-based Communication in WhatsApp}, year = 2016 }
• Burger, V., Seufert, M., Hoßfeld, T., Tran-Gia, P.: Performance Evaluation of Backhaul Bandwidth Aggregation Using a Partial Sharing Scheme. Physical Communication. 19, 135-144 (2016).
  [ Abstract ] [ BibTeX ]
   
  To cope with the increasing demand of mobile devices and the limited capacity of cellular networks mobile connections are offloaded to WiFi. The access capacity is further increased, by aggregating bandwidth of WiFi access links. To analyse the performance of aggregated access links we model the most simple case of two cooperating systems interchanging capacities using an offloading scheme. The resulting analytic model is computed by means of a two-dimensional birth and death process. It can be used to seamlessly evaluate the performance of systems between partitioning and complete sharing. This allows to optimize the setting of thresholds dependent on the load of the cooperating system. Furthermore the benefit of aggregating bandwidth in different scenarios with homogeneous and heterogeneous workloads is quantified and the performance of more than two cooperating systems is evaluated by simulation.
  @article{info3-article-2016-3, abstract = {To cope with the increasing demand of mobile devices and the limited capacity of cellular networks mobile connections are offloaded to WiFi. The access capacity is further increased, by aggregating bandwidth of WiFi access links. To analyse the performance of aggregated access links we model the most simple case of two cooperating systems interchanging capacities using an offloading scheme. The resulting analytic model is computed by means of a two-dimensional birth and death process. It can be used to seamlessly evaluate the performance of systems between partitioning and complete sharing. This allows to optimize the setting of thresholds dependent on the load of the cooperating system. Furthermore the benefit of aggregating bandwidth in different scenarios with homogeneous and heterogeneous workloads is quantified and the performance of more than two cooperating systems is evaluated by simulation.}, author = {Burger, Valentin and Seufert, Michael and Hoßfeld, Tobias and Tran-Gia, Phuoc}, journal = {Physical Communication}, month = 6, pages = {135-144}, title = {Performance Evaluation of Backhaul Bandwidth Aggregation Using a Partial Sharing Scheme}, volume = 19, year = 2016 }
• Seufert, M., Griepentrog, T., Burger, V., Hoßfeld, T.: A Simple WiFi Hotspot Model for Cities. IEEE Communications Letters. 20, 384 - 387 (2016).
  [ Abstract ] [ BibTeX ]
   
  WiFi offloading has become increasingly popular. Many private and public institutions (e.g., libraries, cafes, restaurants) already provide an alternative free Internet link via WiFi, but also commercial services emerge to mitigate the load on mobile networks. Moreover, smart cities start to establish WiFi infrastructure for current and future civic services. In this work, the hotspot locations of ten diverse large cities are characterized, and a surprisingly simple model for the distribution of WiFi hotspots in an urban environment is derived.
  @article{info3-article-2016-2, abstract = {WiFi offloading has become increasingly popular. Many private and public institutions (e.g., libraries, cafes, restaurants) already provide an alternative free Internet link via WiFi, but also commercial services emerge to mitigate the load on mobile networks. Moreover, smart cities start to establish WiFi infrastructure for current and future civic services. In this work, the hotspot locations of ten diverse large cities are characterized, and a surprisingly simple model for the distribution of WiFi hotspots in an urban environment is derived.}, author = {Seufert, Michael and Griepentrog, Tobias and Burger, Valentin and Hoßfeld, Tobias}, journal = {IEEE Communications Letters}, month = 2, number = 2, pages = {384 - 387}, title = {A Simple WiFi Hotspot Model for Cities}, volume = 20, year = 2016 }
• Seufert, M., Lange, S., Hoßfeld, T.: More than Topology: Joint Topology and Attribute Sampling and Generation of Social Network Graphs. Computer Communications. 73, 176-187 (2016).
  [ Abstract ] [ BibTeX ]
   
  Graph sampling refers to the process of deriving a small subset of nodes from a possibly huge graph in order to estimate properties of the whole graph from examining the sample. Whereas topological properties can already be obtained accurately by sampling, current approaches do not take possibly hidden dependencies between node topology and attributes into account. Especially in the context of online social networks, node attributes are of importance as they correspond to properties of the social network's users. Therefore, existing sampling algorithms can be extended to attribute sampling, but still lack the capturing of structural properties. Analyzing topology (e.g., node degree, clustering coefficient) and attribute properties (e.g., age, location) jointly can provide valuable insights into the social network and allows for a better understanding of social processes. As major contribution, this work proposes a novel sampling algorithm which provides unbiased and reliable estimates of joint topological and attribute based graph properties in a resource efficient fashion. Furthermore, the obtained samples allow for the generation of synthetic graphs, which show high similarity to the original graph with respect to topology and attributes. The proposed sampling and generation algorithms are evaluated on real world social network graphs, for which they demonstrate to be effective.
  @article{info3-article-2016-1, abstract = {Graph sampling refers to the process of deriving a small subset of nodes from a possibly huge graph in order to estimate properties of the whole graph from examining the sample. Whereas topological properties can already be obtained accurately by sampling, current approaches do not take possibly hidden dependencies between node topology and attributes into account. Especially in the context of online social networks, node attributes are of importance as they correspond to properties of the social network's users. Therefore, existing sampling algorithms can be extended to attribute sampling, but still lack the capturing of structural properties. Analyzing topology (e.g., node degree, clustering coefficient) and attribute properties (e.g., age, location) jointly can provide valuable insights into the social network and allows for a better understanding of social processes. As major contribution, this work proposes a novel sampling algorithm which provides unbiased and reliable estimates of joint topological and attribute based graph properties in a resource efficient fashion. Furthermore, the obtained samples allow for the generation of synthetic graphs, which show high similarity to the original graph with respect to topology and attributes. The proposed sampling and generation algorithms are evaluated on real world social network graphs, for which they demonstrate to be effective.}, author = {Seufert, Michael and Lange, Stanislav and Hoßfeld, Tobias}, journal = {Computer Communications}, month = 1, number = {Part B}, pages = {176-187}, title = {More than Topology: Joint Topology and Attribute Sampling and Generation of Social Network Graphs}, volume = 73, year = 2016 }
• Gebert, S.: Performance Modeling of Softwarized Network Functions using Discrete-Time Analysis. , Fachgruppentagung ITG 5.2.1, Technische Universität Hamburg-Harburg (2016).
  [ BibTeX ]
   
  @presentation{info3-presentation-2016-6, address = {Fachgruppentagung ITG 5.2.1, Technische Universität Hamburg-Harburg}, author = {Gebert, Steffen}, month = 8, title = {Performance Modeling of Softwarized Network Functions using Discrete-Time Analysis}, year = 2016 }
• Chaplick, S., Fleszar, K., Lipp, F., Ravsky, A., Verbitsky, O., Wolff, A.: Drawing Graphs on Few Lines and Few Planes. In: Hu, Y. und Nöllenburg, M. (hrsg.) Proc. 24th Int. Symp. Graph Drawing & Network Vis. (GD'16). S. 166--180. Springer-Verlag (2016).
  [ BibTeX ] [ URL ] [ DOI ]
   
  @inproceedings{cflrvw-dgflf-GD16, author = {Chaplick, Steven and Fleszar, Krzysztof and Lipp, Fabian and Ravsky, Alexander and Verbitsky, Oleg and Wolff, Alexander}, booktitle = {Proc. 24th Int. Symp. Graph Drawing & Network Vis. (GD'16)}, editor = {Hu, Yifan and Nöllenburg, Martin}, pages = {166--180}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Drawing Graphs on Few Lines and Few Planes}, volume = 9801, year = 2016 }
• van Dijk, T.C., Fink, M., Fischer, N., Lipp, F., Markfelder, P., Ravsky, A., Suri, S., Wolff, A.: Block Crossings in Storyline Visualizations. In: Hu, Y. und Nöllenburg, M. (hrsg.) Proc. 24th Int. Symp. Graph Drawing & Network Vis. (GD'16). S. 382--398. Springer-Verlag (2016).
  [ BibTeX ] [ URL ] [ DOI ]
   
  @inproceedings{dfflmrsw-bcsv-GD16, author = {van Dijk, Thomas C. and Fink, Martin and Fischer, Norbert and Lipp, Fabian and Markfelder, Peter and Ravsky, Alexander and Suri, Subhash and Wolff, Alexander}, booktitle = {Proc. 24th Int. Symp. Graph Drawing & Network Vis. (GD'16)}, editor = {Hu, Yifan and Nöllenburg, Martin}, pages = {382--398}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Block Crossings in Storyline Visualizations}, volume = 9801, year = 2016 }
• Zoller, D., Doerfel, S., Jäschke, R., Stumme, G., Hotho, A.: Posted, Visited, Exported: Altmetrics in the Social Tagging System BibSonomy. Journal of Informetrics. 10, 732 - 749 (2016).
  [ Abstract ] [ BibTeX ] [ URL ] [ DOI ]
   
  In social tagging systems, like Mendeley, CiteULike, and BibSonomy, users can post, tag, visit, or export scholarly publications. In this paper, we compare citations with metrics derived from users’ activities (altmetrics) in the popular social bookmarking system BibSonomy. Our analysis, using a corpus of more than 250,000 publications published before 2010, reveals that overall, citations and altmetrics in BibSonomy are mildly correlated. Furthermore, grouping publications by user-generated tags results in topic-homogeneous subsets that exhibit higher correlations with citations than the full corpus. We find that posts, exports, and visits of publications are correlated with citations and even bear predictive power over future impact. Machine learning classifiers predict whether the number of citations that a publication receives in a year exceeds the median number of citations in that year, based on the usage counts of the preceding year. In that setup, a Random Forest predictor outperforms the baseline on average by seven percentage points.
  @article{zoller2016posted, abstract = {In social tagging systems, like Mendeley, CiteULike, and BibSonomy, users can post, tag, visit, or export scholarly publications. In this paper, we compare citations with metrics derived from users’ activities (altmetrics) in the popular social bookmarking system BibSonomy. Our analysis, using a corpus of more than 250,000 publications published before 2010, reveals that overall, citations and altmetrics in BibSonomy are mildly correlated. Furthermore, grouping publications by user-generated tags results in topic-homogeneous subsets that exhibit higher correlations with citations than the full corpus. We find that posts, exports, and visits of publications are correlated with citations and even bear predictive power over future impact. Machine learning classifiers predict whether the number of citations that a publication receives in a year exceeds the median number of citations in that year, based on the usage counts of the preceding year. In that setup, a Random Forest predictor outperforms the baseline on average by seven percentage points.}, author = {Zoller, Daniel and Doerfel, Stephan and Jäschke, Robert and Stumme, Gerd and Hotho, Andreas}, journal = {Journal of Informetrics}, number = 3, pages = {732 - 749}, title = {Posted, Visited, Exported: Altmetrics in the Social Tagging System BibSonomy}, volume = 10, year = 2016 }
• Fischbach, M., Wiebusch, D., Latoschik, M.E.: Semantics-based Software Techniques for Maintainable Multimodal Input Processing in Real-time Interactive Systems. 9th Workshop on Software Engineering and Architectures for Realtime Interactive Systems (SEARIS). IEEE Computer Society (2016).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  Maintainability, i.e. reusability, modifiability, and modularity, is a critical non-functional quality requirement, especially for software frameworks. Its fulfilment is already challenging for low-interactive application areas. It is additionally complicated by complex system designs of Real-time Interactive Systems (RISs), required for Augmented, Mixed, and Virtual Reality, as well as computer games. If such systems incorporate AI methods, as required for the implementation of multimodal interfaces or smart environments, it is even further exacerbated. Existing approaches strive to establish software technical solutions to support the close temporal and semantic coupling required for multimodal processing and at the same time preserve a general decoupling principle between involved software modules. We present two key solutions that target the semantic coupling issue: (1) a semantics-based access scheme to principal elements of the application state and (2) the specification of effects by means of semantic function descriptions for multimodal processing. Both concepts are modeled in an OWL ontology. The applicability of our concepts is showcased by a prototypical implementation and explained by an interaction example that is applied for two application areas.
  @inproceedings{fischbach2016semanticsbased, abstract = {Maintainability, i.e. reusability, modifiability, and modularity, is a critical non-functional quality requirement, especially for software frameworks. Its fulfilment is already challenging for low-interactive application areas. It is additionally complicated by complex system designs of Real-time Interactive Systems (RISs), required for Augmented, Mixed, and Virtual Reality, as well as computer games. If such systems incorporate AI methods, as required for the implementation of multimodal interfaces or smart environments, it is even further exacerbated. Existing approaches strive to establish software technical solutions to support the close temporal and semantic coupling required for multimodal processing and at the same time preserve a general decoupling principle between involved software modules. We present two key solutions that target the semantic coupling issue: (1) a semantics-based access scheme to principal elements of the application state and (2) the specification of effects by means of semantic function descriptions for multimodal processing. Both concepts are modeled in an OWL ontology. The applicability of our concepts is showcased by a prototypical implementation and explained by an interaction example that is applied for two application areas.}, author = {Fischbach, Martin and Wiebusch, Dennis and Latoschik, Marc Erich}, booktitle = {9th Workshop on Software Engineering and Architectures for Realtime Interactive Systems (SEARIS)}, publisher = {IEEE Computer Society}, title = {Semantics-based Software Techniques for Maintainable Multimodal Input Processing in Real-time Interactive Systems}, year = 2016 }
• Löffler, A., van Dijk, T.C., Wolff, A.: Snapping Graph Drawings to the Grid Optimally. In: Hu, Y. und Nöllenburg, M. (hrsg.) Proc. 24th Int. Symp. Graph Drawing & Network Vis. (GD'16). S. 144--151. Springer-Verlag (2016).
  [ BibTeX ] [ URL ] [ DOI ]
   
  @inproceedings{ldw-sgdgo-GD16, author = {Löffler, Andre and van Dijk, Thomas C. and Wolff, Alexander}, booktitle = {Proc. 24th Int. Symp. Graph Drawing & Network Vis. (GD'16)}, editor = {Hu, Yifan and Nöllenburg, Martin}, pages = {144--151}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Snapping Graph Drawings to the Grid Optimally}, volume = 9801, year = 2016 }
• Kindermann, P., Niedermann, B., Rutter, I., Schaefer, M., Schulz, A., Wolff, A.: Multi-Sided Boundary Labeling. Algorithmica. 76, 225--258 (2016).
  [ Abstract ] [ BibTeX ] [ URL ] [ DOI ]
   
  In the emphBoundary Labeling problem, we are given a set of \($n$\) points, referred to as emphsites, inside an axis-parallel rectangle \($R$\), and a set of n pairwise disjoint rectangular labels that are attached to \($R$\) from the outside. The task is to connect the sites to the labels by non-intersecting rectilinear paths, so-called leaders, with at most one bend. In this paper, we study the emphMulti-Sided Boundary Labeling problem, with labels lying on at least two sides of the enclosing rectangle. We present a polynomial-time algorithm that computes a crossing-free leader layout if one exists. So far, such an algorithm has only been known for the cases in which labels lie on one side or on two opposite sides of \($R$\) (here a crossing-free solution always exists). The case where labels may lie on adjacent sides is more difficult. We present efficient algorithms for testing the existence of a crossing-free leader layout that labels all sites and also for maximizing the number of labeled sites in a crossing-free leader layout. For two-sided boundary labeling with adjacent sides, we further show how to minimize the total leader length in a crossing-free layout.
  @article{knrssw-tsblas-Algorithmica16, abstract = {In the emphBoundary Labeling problem, we are given a set of \($n$\) points, referred to as emphsites, inside an axis-parallel rectangle \($R$\), and a set of n pairwise disjoint rectangular labels that are attached to \($R$\) from the outside. The task is to connect the sites to the labels by non-intersecting rectilinear paths, so-called leaders, with at most one bend. In this paper, we study the emphMulti-Sided Boundary Labeling problem, with labels lying on at least two sides of the enclosing rectangle. We present a polynomial-time algorithm that computes a crossing-free leader layout if one exists. So far, such an algorithm has only been known for the cases in which labels lie on one side or on two opposite sides of \($R$\) (here a crossing-free solution always exists). The case where labels may lie on adjacent sides is more difficult. We present efficient algorithms for testing the existence of a crossing-free leader layout that labels all sites and also for maximizing the number of labeled sites in a crossing-free leader layout. For two-sided boundary labeling with adjacent sides, we further show how to minimize the total leader length in a crossing-free layout.}, author = {Kindermann, Philipp and Niedermann, Benjamin and Rutter, Ignaz and Schaefer, Marcus and Schulz, André and Wolff, Alexander}, journal = {Algorithmica}, number = 1, pages = {225--258}, title = {Multi-Sided Boundary Labeling}, volume = 76, year = 2016 }
• Evans, W.S., Fleszar, K., Kindermann, P., Saeedi, N., Shin, C.-S., Wolff, A.: Minimum Rectilinear Polygons for Given Angle Sequences. In: Akiyama, J., Ito, H., und Sakai, T. (hrsg.) Proc. Japan. Conf. Discrete Comput. Geom. Graphs (JCDCGG'16). S. 105--119. Springer-Verlag (2016).
  [ BibTeX ] [ URL ] [ DOI ]
   
  @inproceedings{efkssw-mrpga-JCDCGG16, author = {Evans, William S. and Fleszar, Krzysztof and Kindermann, Philipp and Saeedi, Noushin and Shin, Chan-Su and Wolff, Alexander}, booktitle = {Proc. Japan. Conf. Discrete Comput. Geom. Graphs (JCDCGG'16)}, editor = {Akiyama, Jin and Ito, Hiro and Sakai, Toshinori}, pages = {105--119}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Minimum Rectilinear Polygons for Given Angle Sequences}, volume = 9943, year = 2016 }
• Filar, K.: Evaluation of Energy Efficiency Measurements for Virtualized Network Functions, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2016-12, author = {Filar, Kamil}, month = 7, school = {University of Wuerzburg}, title = {Evaluation of Energy Efficiency Measurements for Virtualized Network Functions}, year = 2016 }
• Agüero, R., Zinner, T., García-Lozano, M., Wenning, B.-L., Timm-Giel, A.: Mobile Networks and Management. Springer, Santander, Spain (2016).
  [ BibTeX ]
   
  @book{info3-book-2016-1, address = {Santander, Spain}, author = {Agüero, Ramón and Zinner, Thomas and García-Lozano, Mario and Wenning, Bernd-Ludwig and Timm-Giel, Andreas}, booktitle = {6th International Conference (MONAMI 2014), September 22-26, 2014, Revised Selected Papers}, publisher = {Springer}, title = {Mobile Networks and Management}, year = 2016 }
• Ott, S.: Browser-based Measurements of HTTP Live Streaming Performance, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2016-1, author = {Ott, Stefan}, month = 3, school = {University of Wuerzburg}, title = {Browser-based Measurements of HTTP Live Streaming Performance}, year = 2016 }
• Cofano, G., De Cicco, L., Zinner, T., Nguyen-Ngoc, A., Tran-Gia, P., Mascolo, S.: Design and Experimental Evaluation of Network-assisted Strategies for HTTP Adaptive Video Streaming. Best Student Paper Award, ACM Multimedia Systems Conference (MMSys). , Klagenfurt, Austria (2016).
  [ Abstract ] [ BibTeX ]
   
  In this paper we investigate several network-assisted streaming approaches which rely on active cooperation between video streaming applications and the network. We build a Video Control Plane which enforces Video Quality Fairness among concurrent video flows generated by heterogeneous client devices. To the purpose, a max-min fairness optimization problem is solved at run-time. We compare two approaches to actuate the optimal solution in an SDN network: the first one allocating network bandwidth slices to video flows, the second one guiding video players in the video bitrate selection. Performance is assessed through several QoE-related metrics, such as Video Quality Fairness, video quality, and switching frequency. The impact of client-side adaptation algorithms is also investigated.
  @inproceedings{info3-inproceedings-2016-3, abstract = {In this paper we investigate several network-assisted streaming approaches which rely on active cooperation between video streaming applications and the network. We build a Video Control Plane which enforces Video Quality Fairness among concurrent video flows generated by heterogeneous client devices. To the purpose, a max-min fairness optimization problem is solved at run-time. We compare two approaches to actuate the optimal solution in an SDN network: the first one allocating network bandwidth slices to video flows, the second one guiding video players in the video bitrate selection. Performance is assessed through several QoE-related metrics, such as Video Quality Fairness, video quality, and switching frequency. The impact of client-side adaptation algorithms is also investigated.}, address = {Klagenfurt, Austria}, author = {Cofano, Guiseppe and De Cicco, Luca and Zinner, Thomas and Nguyen-Ngoc, Anh and Tran-Gia, Phuoc and Mascolo, Saverio}, booktitle = {Best Student Paper Award, ACM Multimedia Systems Conference (MMSys)}, month = 5, title = {Design and Experimental Evaluation of Network-assisted Strategies for HTTP Adaptive Video Streaming}, year = 2016 }
• Tavakoli, S., Egger, S., Seufert, M., Schatz, R., Brunnström, K., García, N.: Perceptual Quality of HTTP Adaptive Streaming Strategies: Cross-Experimental Analysis of Multi-Laboratory and Crowdsourced Subjective Studies. IEEE Journal on Selected Areas in Communications. 34, 2141-2153 (2016).
  [ Abstract ] [ BibTeX ]
   
  Today’s packet-switched networks are subject to bandwidth fluctuations that cause for degradation of user experience of multimedia services. In order to cope with this problem, HTTP Adaptive Streaming (HAS) has been proposed in recent years as a video delivery solution for the future Internet and being adopted by an increasing number of streaming services such as Netflix and Youtube. HAS enables service providers to improve users’ Quality of Experience (QoE) and network resource utilization by adapting the quality of the video stream to the current network conditions. However, the resulting timevarying video quality caused by adaptation introduces a new type of impairment and thus novel QoE research challenges. Despite of various recent attempts to investigate these challenges, many fundamental questions regarding HAS perceptual performance are still open. In this paper, the QoE impact of different technical adaptation parameters including chunk length, switching amplitude, switching frequency and temporal recency are investigated. In addition, the influence of content on perceptual quality of these parameters is analyzed. To this end, a large number of adaptation scenarios have been subjectively evaluated in four laboratory experiments and one crowdsourcing study. Statistical analysis of the combined dataset reveals results that partly contradict widely held assumptions and provide novel insights in perceptual quality of adapted video sequences, e.g. interaction effects between quality switching direction (up/down) and switching strategy (smooth/abrupt). The large variety of experimental configurations across different studies ensures the consistency and external validity of the presented results that can be utilized for enhancing the perceptual performance of adaptive streaming services.
  @article{info3-article-2016-5, abstract = {Today’s packet-switched networks are subject to bandwidth fluctuations that cause for degradation of user experience of multimedia services. In order to cope with this problem, HTTP Adaptive Streaming (HAS) has been proposed in recent years as a video delivery solution for the future Internet and being adopted by an increasing number of streaming services such as Netflix and Youtube. HAS enables service providers to improve users’ Quality of Experience (QoE) and network resource utilization by adapting the quality of the video stream to the current network conditions. However, the resulting timevarying video quality caused by adaptation introduces a new type of impairment and thus novel QoE research challenges. Despite of various recent attempts to investigate these challenges, many fundamental questions regarding HAS perceptual performance are still open. In this paper, the QoE impact of different technical adaptation parameters including chunk length, switching amplitude, switching frequency and temporal recency are investigated. In addition, the influence of content on perceptual quality of these parameters is analyzed. To this end, a large number of adaptation scenarios have been subjectively evaluated in four laboratory experiments and one crowdsourcing study. Statistical analysis of the combined dataset reveals results that partly contradict widely held assumptions and provide novel insights in perceptual quality of adapted video sequences, e.g. interaction effects between quality switching direction (up/down) and switching strategy (smooth/abrupt). The large variety of experimental configurations across different studies ensures the consistency and external validity of the presented results that can be utilized for enhancing the perceptual performance of adaptive streaming services.}, author = {Tavakoli, Samira and Egger, Sebastian and Seufert, Michael and Schatz, Raimund and Brunnström, Kjell and García, Narciso}, journal = {IEEE Journal on Selected Areas in Communications}, month = 6, number = 8, pages = {2141-2153}, title = {Perceptual Quality of HTTP Adaptive Streaming Strategies: Cross-Experimental Analysis of Multi-Laboratory and Crowdsourced Subjective Studies}, volume = 34, year = 2016 }
• Hirth, M., Allendorf, F., Metzger, F., Schwartz, C.: Assessing the Accuracy of Network Estimations in the DOTA 2 Game Client. Workshop on Perceptual Quality of Systems (PQS). , Berlin, Germany (2016).
  [ Abstract ] [ BibTeX ]
   
  Online video games and the subjective quality of player inter- actions with them rely on good network conditions. Almost equally important is a good and timely knowledge of such conditions in order to take proper countermeasures to worsening conditions. To this end, many online video games include components for estimating the current network status. In this paper, we examine the accuracy of those estimations for the popular competitive multiplayer game DOTA 2. Our results show that the game client is capable of performing a good estimation of the delay and packet loss, but only after a rather large initial delay.
  @inproceedings{info3-inproceedings-2016-13, abstract = {Online video games and the subjective quality of player inter- actions with them rely on good network conditions. Almost equally important is a good and timely knowledge of such conditions in order to take proper countermeasures to worsening conditions. To this end, many online video games include components for estimating the current network status. In this paper, we examine the accuracy of those estimations for the popular competitive multiplayer game DOTA 2. Our results show that the game client is capable of performing a good estimation of the delay and packet loss, but only after a rather large initial delay.}, address = {Berlin, Germany}, author = {Hirth, Matthias and Allendorf, Fabian and Metzger, Florian and Schwartz, Christian}, booktitle = {Workshop on Perceptual Quality of Systems (PQS)}, month = 8, title = {Assessing the Accuracy of Network Estimations in the DOTA 2 Game Client}, year = 2016 }
• Krzysztof Fleszar, M.M.: New Algorithms for Disjoint Paths Based on Tree-Likeness. Proc. 24th European Symposium on Algorithms (ESA '16) (2016).
  [ BibTeX ] [ URL ]
   
  @inproceedings{fleszar-etal:disjoint-paths, author = {Krzysztof Fleszar, Matthias Mnich, Joachim Spoerhase}, booktitle = {Proc. 24th European Symposium on Algorithms (ESA '16)}, note = {Accepted}, title = {New Algorithms for Disjoint Paths Based on Tree-Likeness}, year = 2016 }
• Geissler, S.: Mining Vulnerability Databases for Information on Hypervisor Vulnerabilities: Analyses and Predictions, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2016-1, author = {Geissler, Stefan}, month = 2, school = {University of Würzburg}, title = {Mining Vulnerability Databases for Information on Hypervisor Vulnerabilities: Analyses and Predictions}, year = 2016 }
• Seufert, M.: Adaptive Videostreaming and QoE. , HUST Spring School, Würzburg, Germany (2016).
  [ BibTeX ]
   
  @presentation{info3-presentation-2016-3, address = {HUST Spring School, Würzburg, Germany}, author = {Seufert, Michael}, month = 2, title = {Adaptive Videostreaming and QoE}, year = 2016 }
• Seufert, M.: Impact of Test Condition Selection in Adaptive Crowdsourcing Studies on Subjective Quality. , 8th International Conference on Quality of Multimedia Experience (QoMEX), Lisbon, Portugal (2016).
  [ BibTeX ]
   
  @presentation{info3-presentation-2016-2, address = {8th International Conference on Quality of Multimedia Experience (QoMEX), Lisbon, Portugal}, author = {Seufert, Michael}, month = 6, title = {Impact of Test Condition Selection in Adaptive Crowdsourcing Studies on Subjective Quality}, year = 2016 }
• Seufert, M., Lange, S., Meixner, M.: Automated Decision Making Methods for the Multi-objective Optimization Task of Cloud Service Placement. 1st International Workshop on Programmability for Cloud Networks and Applications (PROCON). , Würzburg, Germany (2016).
  [ BibTeX ]
   
  @inproceedings{info3-inproceedings-2016-12, address = {Würzburg, Germany}, author = {Seufert, Michael and Lange, Stanislav and Meixner, Markus}, booktitle = {1st International Workshop on Programmability for Cloud Networks and Applications (PROCON)}, month = 9, title = {Automated Decision Making Methods for the Multi-objective Optimization Task of Cloud Service Placement}, year = 2016 }
• Seufert, M., Hoßfeld, T.: One Shot Crowdtesting: Approaching the Extremes of Crowdsourced Subjective Quality Testing. 5th ISCA/DEGA Workshop on Perceptual Quality of Systems (PQS). , Berlin, Germany (2016).
  [ Abstract ] [ BibTeX ]
   
  Crowdsourcing studies for subjective quality testing have become a particularly useful tool for Quality of Experience researchers. Typically, crowdsouring studies are conducted by many unsupervised workers, which rate the perceived quality of several test conditions during one session (mixed within-subject test design). However, those studies often show to be very sensitive, for example, to test instructions, design, and filtering of unreliable participants. Moreover, the exposure of several test conditions to single workers potentially leads to an implicit training and anchoring of ratings. Therefore, this works investigates the extreme case of presenting only a single test condition to each worker (completely between-subjects test design). The results are compared to a typical crowdsourcing study design with multiple test conditions to discuss training effects in crowdsourcing studies. Thus, this work investigates if it is possible to use a simple ``one shot'' design with only one rating of a large number of workers instead of sophisticated (mixed or within-subject) test designs in crowdsourcing.
  @inproceedings{info3-inproceedings-2016-11, abstract = {Crowdsourcing studies for subjective quality testing have become a particularly useful tool for Quality of Experience researchers. Typically, crowdsouring studies are conducted by many unsupervised workers, which rate the perceived quality of several test conditions during one session (mixed within-subject test design). However, those studies often show to be very sensitive, for example, to test instructions, design, and filtering of unreliable participants. Moreover, the exposure of several test conditions to single workers potentially leads to an implicit training and anchoring of ratings. Therefore, this works investigates the extreme case of presenting only a single test condition to each worker (completely between-subjects test design). The results are compared to a typical crowdsourcing study design with multiple test conditions to discuss training effects in crowdsourcing studies. Thus, this work investigates if it is possible to use a simple ``one shot'' design with only one rating of a large number of workers instead of sophisticated (mixed or within-subject) test designs in crowdsourcing.}, address = {Berlin, Germany}, author = {Seufert, Michael and Hoßfeld, Tobias}, booktitle = {5th ISCA/DEGA Workshop on Perceptual Quality of Systems (PQS)}, month = 8, title = {One Shot Crowdtesting: Approaching the Extremes of Crowdsourced Subjective Quality Testing}, year = 2016 }
• Seufert, M., Zach, O., Hoßfeld, T., Slanina, M., Tran-Gia, P.: Impact of Test Condition Selection in Adaptive Crowdsourcing Studies on Subjective Quality. 8th International Conference on Quality of Multimedia Experience (QoMEX). , Lisbon, Portugal (2016).
  [ Abstract ] [ BibTeX ]
   
  Adaptive crowdsourcing is a new approach to crowdsourced Quality of Experience (QoE) studies, which aims to improve the certainty of resulting QoE models by adaptively distributing a fixed budget of user ratings to the test conditions. The main idea of the adaptation is to dynamically allocate the next rating to a condition, for which the submitted ratings so far show a low certainty. This paper investigates the effects of statistical adaptation on the distribution of ratings and the goodness of the resulting QoE models. Thereby, it gives methodological advice how to select test conditions for future crowdsourced QoE studies.
  @inproceedings{info3-inproceedings-2016-10, abstract = {Adaptive crowdsourcing is a new approach to crowdsourced Quality of Experience (QoE) studies, which aims to improve the certainty of resulting QoE models by adaptively distributing a fixed budget of user ratings to the test conditions. The main idea of the adaptation is to dynamically allocate the next rating to a condition, for which the submitted ratings so far show a low certainty. This paper investigates the effects of statistical adaptation on the distribution of ratings and the goodness of the resulting QoE models. Thereby, it gives methodological advice how to select test conditions for future crowdsourced QoE studies.}, address = {Lisbon, Portugal}, author = {Seufert, Michael and Zach, Ondrej and Hoßfeld, Tobias and Slanina, Martin and Tran-Gia, Phuoc}, booktitle = {8th International Conference on Quality of Multimedia Experience (QoMEX)}, month = 6, title = {Impact of Test Condition Selection in Adaptive Crowdsourcing Studies on Subjective Quality}, year = 2016 }
• Burger, V., Frances Pajo, J., Sanchez, O.R., Seufert, M., Schwartz, C., Wamser, F., Davoli, F., Tran-Gia, P.: Load Dynamics of a Multiplayer Online Battle Area and Simulative Assessment of Edge Server Placements. ACM Multimedia Systems Conference (MMSys). , Klagenfurt, Austria (2016).
  [ Abstract ] [ BibTeX ]
   
  Free-to-play models, streaming of games and eSports are reasons for online gaming to grow in popularity recently. On the forefront are multiplayer online battle arenas, which gain high popularity by introducing a competitive format that is easy to access and requires cooperation and team play. These games highly rely on fast reaction of the players, which makes latency the key performance indicator of such applications. To obtain low latency, this paper proposes moving game servers close to players towards the edge of the network. The performance of such mechanism highly depends on the geographic distribution of players. By analyzing match histories and statistics, we develop models for the arrival process and location of game requests. This allows us to evaluate the performance of edge server resource migration policies in an event based simulation. Our results show that a high number of edge servers is preferable compared to few larger edge servers to reduce the latency of players. This supports approaches that allow deploying virtual server instances in the back-haul.
  @inproceedings{info3-inproceedings-2016-2, abstract = {Free-to-play models, streaming of games and eSports are reasons for online gaming to grow in popularity recently. On the forefront are multiplayer online battle arenas, which gain high popularity by introducing a competitive format that is easy to access and requires cooperation and team play. These games highly rely on fast reaction of the players, which makes latency the key performance indicator of such applications. To obtain low latency, this paper proposes moving game servers close to players towards the edge of the network. The performance of such mechanism highly depends on the geographic distribution of players. By analyzing match histories and statistics, we develop models for the arrival process and location of game requests. This allows us to evaluate the performance of edge server resource migration policies in an event based simulation. Our results show that a high number of edge servers is preferable compared to few larger edge servers to reduce the latency of players. This supports approaches that allow deploying virtual server instances in the back-haul.}, address = {Klagenfurt, Austria}, author = {Burger, Valentin and Frances Pajo, Jane and Sanchez, Odnan Ref and Seufert, Michael and Schwartz, Christian and Wamser, Florian and Davoli, Franco and Tran-Gia, Phuoc}, booktitle = {ACM Multimedia Systems Conference (MMSys)}, month = 5, title = {Load Dynamics of a Multiplayer Online Battle Area and Simulative Assessment of Edge Server Placements}, year = 2016 }
• Haunert, J.-H., Wolff, A.: Beyond Maximum Independent Set: An Extended Model for Point-Feature Label Placement. Proc. ISPRS (Commission II, WG II/2). S. 109--114 (2016).
  [ BibTeX ] [ URL ] [ DOI ]
   
  @inproceedings{hw-bmise-ISPRS16, author = {Haunert, Jan-Henrik and Wolff, Alexander}, booktitle = {Proc. ISPRS (Commission II, WG II/2)}, pages = {109--114}, title = {Beyond Maximum Independent Set: An Extended Model for Point-Feature Label Placement}, volume = {XLI-B2}, year = 2016 }
• Gebert, S., Geissler, S., Zinner, T., Nguyen-Ngoc, A., Lange, S., Tran-Gia, P.: ZOOM: Lightweight SDN-based Elephant Detection. First International Workshop on Programmability for Cloud Networks and Applications (PROCON). , Würzburg, Germany (2016).
  [ Abstract ] [ BibTeX ]
   
  Software Defined Networking (SDN) offers a holistic view of the network through a centralized control plane. Consequently, routing decisions can be made based on global knowledge about the network topology as well as its current state. As long living flows are suitable candidates for rerouting, their detection is crucial for efficient flow based traffic management. This work proposes the ZOOM algorithm for elephant detection in SDN networks. To this end, ZOOM follows a very lightweight approach that only uses packet counters implemented by OpenFlow switches and thus does not require any additional hardware. By exploiting this feature of OpenFlow switches, ZOOM allows lightweight and cost-effective elephant detection.
  @inproceedings{info3-inproceedings-2016-8, abstract = {Software Defined Networking (SDN) offers a holistic view of the network through a centralized control plane. Consequently, routing decisions can be made based on global knowledge about the network topology as well as its current state. As long living flows are suitable candidates for rerouting, their detection is crucial for efficient flow based traffic management. This work proposes the ZOOM algorithm for elephant detection in SDN networks. To this end, ZOOM follows a very lightweight approach that only uses packet counters implemented by OpenFlow switches and thus does not require any additional hardware. By exploiting this feature of OpenFlow switches, ZOOM allows lightweight and cost-effective elephant detection.}, address = {Würzburg, Germany}, author = {Gebert, Steffen and Geissler, Stefan and Zinner, Thomas and Nguyen-Ngoc, Anh and Lange, Stanislav and Tran-Gia, Phuoc}, booktitle = {First International Workshop on Programmability for Cloud Networks and Applications (PROCON)}, month = 9, title = {ZOOM: Lightweight SDN-based Elephant Detection}, year = 2016 }
• Lipp, F., Wolff, A., Zink, J.: Faster Force-Directed Graph Drawing with the Well-Separated Pair Decomposition. Algorithms. 9, article 53, 17 pages (2016).
  [ Abstract ] [ BibTeX ] [ URL ] [ DOI ]
   
  The force-directed paradigm is one of the few generic approaches to drawing graphs. Since force-directed algorithms can be extended easily, they are used frequently. Most of these algorithms are, however, quite slow on large graphs, as they compute a quadratic number of forces in each iteration. We give a new algorithm that takes only \($O(m+n \log n)$\) time per iteration when laying out a graph with \($n$\) vertices and \($m$\) edges. Our algorithm approximates the true forces using the so-called well-separated pair decomposition. We perform experiments on a large number of graphs and show that we can strongly reduce the runtime, even on graphs with less than a hundred vertices, without a significant influence on the quality of the drawings (in terms of the number of crossings and deviation in edge lengths).
  @article{lwz-ffdgd-Algorithms16, abstract = {The force-directed paradigm is one of the few generic approaches to drawing graphs. Since force-directed algorithms can be extended easily, they are used frequently. Most of these algorithms are, however, quite slow on large graphs, as they compute a quadratic number of forces in each iteration. We give a new algorithm that takes only \($O(m+n \log n)$\) time per iteration when laying out a graph with \($n$\) vertices and \($m$\) edges. Our algorithm approximates the true forces using the so-called well-separated pair decomposition. We perform experiments on a large number of graphs and show that we can strongly reduce the runtime, even on graphs with less than a hundred vertices, without a significant influence on the quality of the drawings (in terms of the number of crossings and deviation in edge lengths).}, author = {Lipp, Fabian and Wolff, Alexander and Zink, Johannes}, journal = {Algorithms}, number = 3, pages = {article 53, 17 pages}, title = {Faster Force-Directed Graph Drawing with the Well-Separated Pair Decomposition}, volume = 9, year = 2016 }
• Nguyen-Ngoc, A., Lange, S., Gebert, S., Zinner, T., Tran-Gia, P., Jarschel, M.: Performance Evaluation Mechanisms for FlowMod Message Processing in OpenFlow Switches. IEEE Sixth International Conference on Communications and Electronics. , Ha Long City, Vietnam (2016).
  [ Abstract ] [ BibTeX ]
   
  Network operators can benefit in terms of flexibility, cost, and vendor-independence when adopting the Software Defined Networking (SDN) paradigm. In many scenarios, the SDN controller orders the installation of new flow table entries in the switches it manages. Since such operations are handled in the slow path of the switches, the corresponding processing times constitute an important performance indicator for switches. This work focuses on a comparison of two mechanisms for evaluating the performance of OpenFlow switches with respect to the processing time of FlowMod messages. These mechanisms are characterized by different degrees of accuracy, cost, complexity, and the capability of performing measurements at run time. The first mechanism is based on the Spirent C1 dedicated testing platform, while the other uses a software module for the OpenDaylight controller. We assess their capabilities with respect to the abovementioned characteristics and quantify their accuracy by means of wiretaps that provide a ground truth regarding the measured processing times. By using three different switches in the experiments, it is possible to distinguish between hardware specific side-effects and general phenomena.
  @inproceedings{info3-inproceedings-2016-7, abstract = {Network operators can benefit in terms of flexibility, cost, and vendor-independence when adopting the Software Defined Networking (SDN) paradigm. In many scenarios, the SDN controller orders the installation of new flow table entries in the switches it manages. Since such operations are handled in the slow path of the switches, the corresponding processing times constitute an important performance indicator for switches. This work focuses on a comparison of two mechanisms for evaluating the performance of OpenFlow switches with respect to the processing time of FlowMod messages. These mechanisms are characterized by different degrees of accuracy, cost, complexity, and the capability of performing measurements at run time. The first mechanism is based on the Spirent C1 dedicated testing platform, while the other uses a software module for the OpenDaylight controller. We assess their capabilities with respect to the abovementioned characteristics and quantify their accuracy by means of wiretaps that provide a ground truth regarding the measured processing times. By using three different switches in the experiments, it is possible to distinguish between hardware specific side-effects and general phenomena.}, address = {Ha Long City, Vietnam}, author = {Nguyen-Ngoc, Anh and Lange, Stanislav and Gebert, Steffen and Zinner, Thomas and Tran-Gia, Phuoc and Jarschel, Michael}, booktitle = {IEEE Sixth International Conference on Communications and Electronics}, month = 7, title = {Performance Evaluation Mechanisms for FlowMod Message Processing in OpenFlow Switches}, year = 2016 }
• Scherer, K.P., Germann, M., Knoell, D., Baumeister, J., Furth, S.: Wissensgenerierung durch Selbstlernverfahren mit strukturierten Katarakt-Daten. Spektrum für Augenheilkunde. 2, 90 (2016).
  [ BibTeX ]
   
  @article{scherer2016wissensgenerierung, author = {Scherer, Klaus Peter and Germann, Markus and Knoell, Daniel and Baumeister, Joachim and Furth, Sebastian}, journal = {Spektrum für Augenheilkunde}, pages = 90, title = {Wissensgenerierung durch Selbstlernverfahren mit strukturierten Katarakt-Daten}, volume = 2, year = 2016 }
• Casas, P., Seufert, M., Wamser, F., Gardlo, B., Sackl, A., Schatz, R.: Next to You: Monitoring Quality of Experience in Cellular Networks from the End-devices. IEEE Transactions on Network and Service Management. 13, 181-196 (2016).
  [ Abstract ] [ BibTeX ]
   
  A quarter of the world population will be using smartphones to access the Internet in the near future. In this context, understanding the Quality of Experience (QoE) of popular apps in such devices becomes paramount to cellular network operators, who need to offer high quality levels to reduce the risks of customers churning for quality dissatisfaction. In this paper we address the problem of QoE provisioning in smartphones from a double perspective, combining the results obtained from subjective lab tests with end-device passive measurements and QoE crowd-sourced feedback obtained in operational cellular networks. The study addresses the impact of both access bandwidth and latency on the QoE of five different services and mobile apps: YouTube, Facebook, Web browsing through Chrome, Google Maps, and WhatsApp. We evaluate the influence of both constant and dynamically changing network access conditions, tackling in particular the case of fluctuating downlink bandwidth, which is typical in cellular networks. As a main contribution, we show that the results obtained in the lab are highly applicable in the live scenario, as mappings track the QoE provided by users in real networks. We additionally provide hints and bandwidth thresholds for good QoE levels on such apps, as well as discussion on end-device passive measurements and analysis. The results presented in this paper provide a sound basis to better understand the QoE requirements of popular mobile apps, as well as for monitoring the underlying provisioning network. To the best of our knowledge, this is the first paper providing such a comprehensive analysis of QoE in mobile devices, combining network measurements with users QoE feedback in lab tests and operational networks.
  @article{info3-article-2016-4, abstract = {A quarter of the world population will be using smartphones to access the Internet in the near future. In this context, understanding the Quality of Experience (QoE) of popular apps in such devices becomes paramount to cellular network operators, who need to offer high quality levels to reduce the risks of customers churning for quality dissatisfaction. In this paper we address the problem of QoE provisioning in smartphones from a double perspective, combining the results obtained from subjective lab tests with end-device passive measurements and QoE crowd-sourced feedback obtained in operational cellular networks. The study addresses the impact of both access bandwidth and latency on the QoE of five different services and mobile apps: YouTube, Facebook, Web browsing through Chrome, Google Maps, and WhatsApp. We evaluate the influence of both constant and dynamically changing network access conditions, tackling in particular the case of fluctuating downlink bandwidth, which is typical in cellular networks. As a main contribution, we show that the results obtained in the lab are highly applicable in the live scenario, as mappings track the QoE provided by users in real networks. We additionally provide hints and bandwidth thresholds for good QoE levels on such apps, as well as discussion on end-device passive measurements and analysis. The results presented in this paper provide a sound basis to better understand the QoE requirements of popular mobile apps, as well as for monitoring the underlying provisioning network. To the best of our knowledge, this is the first paper providing such a comprehensive analysis of QoE in mobile devices, combining network measurements with users QoE feedback in lab tests and operational networks.}, author = {Casas, Pedro and Seufert, Michael and Wamser, Florian and Gardlo, Bruno and Sackl, Andreas and Schatz, Raimund}, journal = {IEEE Transactions on Network and Service Management}, month = 3, number = 2, pages = {181-196}, title = {Next to You: Monitoring Quality of Experience in Cellular Networks from the End-devices}, volume = 13, year = 2016 }
• Stauffert, J.-P., Niebling, F., Latoschik, M.E.: Reducing Application-Stage Latencies For Real-Time Interactive Systems. 9th Workshop on Software Engineering and Architectures for Realtime Interactive Systems (SEARIS). IEEE Computer Society (2016).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  Latency is a pressing problem in Virtual Reality (VR) applications. Low latencies are required for VR to reduce perceptual artifacts and cyber sickness. Additionally, latency jitter denotes the variance in the pattern of latency changes which additionally may cause unwanted effects. This paper analyzes latency jitter caused by typical inter-thread communication (ITC) techniques commonly used in today’s computer systems employed for VR, the influence of the operating system scheduler, and the effect of different garbage collection (GC) methods to understand their effect on latency spikes, here for different Java Virtual Machines (JVM). We measure the scalability and latencies for various ITC techniques with an increasing number of threads and actors performing prototypical concurrent tasks. Four different benchmark implementations on a vanilla Linux kernel as well as on a real-time (RT) Linux kernel assess if a RT variant of a multiuser multiprocess operating system can prevent latency spikes and how this behavior would apply to different programming languages and ITC techniques. We confirmed that scheduler and prioritization of the VR application both play an important role and identified the impact they have on the implementation strategies. Also, Linux RT can limit the latency jitter at the cost of throughput for certain implementations. As expected, the choice of a GC method also is critical and will change the latency patterns drastically. As a result, we suggest that coarse grained concurrency should be employed to avoid adding up of scheduler latencies and unwanted latency jitter for the native ITC case, while actor systems are found to support a higher degree of concurrency granularity and a higher level of abstraction.
  @inproceedings{stauffert2016reducing, abstract = {Latency is a pressing problem in Virtual Reality (VR) applications. Low latencies are required for VR to reduce perceptual artifacts and cyber sickness. Additionally, latency jitter denotes the variance in the pattern of latency changes which additionally may cause unwanted effects. This paper analyzes latency jitter caused by typical inter-thread communication (ITC) techniques commonly used in today’s computer systems employed for VR, the influence of the operating system scheduler, and the effect of different garbage collection (GC) methods to understand their effect on latency spikes, here for different Java Virtual Machines (JVM). We measure the scalability and latencies for various ITC techniques with an increasing number of threads and actors performing prototypical concurrent tasks. Four different benchmark implementations on a vanilla Linux kernel as well as on a real-time (RT) Linux kernel assess if a RT variant of a multiuser multiprocess operating system can prevent latency spikes and how this behavior would apply to different programming languages and ITC techniques. We confirmed that scheduler and prioritization of the VR application both play an important role and identified the impact they have on the implementation strategies. Also, Linux RT can limit the latency jitter at the cost of throughput for certain implementations. As expected, the choice of a GC method also is critical and will change the latency patterns drastically. As a result, we suggest that coarse grained concurrency should be employed to avoid adding up of scheduler latencies and unwanted latency jitter for the native ITC case, while actor systems are found to support a higher degree of concurrency granularity and a higher level of abstraction.}, author = {Stauffert, Jan-Philipp and Niebling, Florian and Latoschik, Marc Erich}, booktitle = {9th Workshop on Software Engineering and Architectures for Realtime Interactive Systems (SEARIS)}, publisher = {IEEE Computer Society}, title = {Reducing Application-Stage Latencies For Real-Time Interactive Systems}, year = 2016 }
• Gebert, S., Zinner, T., Gray, N., Durner, R., Lorenz, C., Lange, S.: Demonstrating a Personalized Secure-By-Default Bring Your Own Device Solution Based on Software Defined Networking, (2016).
  [ Abstract ] [ BibTeX ]
   
  Network virtualization is one classical use-case for Software Defined Networks (SDN). By programmatically instantiating virtual networks, traffic from one or more devices can be separated or connectivity can be established as needed. S- BYOD, which is presented in this demonstration, applies the SDN concept to Bring Your Own Device (BYOD) scenarios and offers personalized virtual networks that are set up and extended on demand. This is done once the user authenticates, activates access to additional applications, or as soon as applications scale out and involve more servers. The described proof-of-concept implementation explores, to what degree an agent-less BYOD solution, based only on SDN, can lower the attack surface by explicit user opt-ins for particular services. Further, an assessment of the number of required rules within the flow tables of switches completes this work.
  @misc{info3-demo-2016-1, abstract = {Network virtualization is one classical use-case for Software Defined Networks (SDN). By programmatically instantiating virtual networks, traffic from one or more devices can be separated or connectivity can be established as needed. S- BYOD, which is presented in this demonstration, applies the SDN concept to Bring Your Own Device (BYOD) scenarios and offers personalized virtual networks that are set up and extended on demand. This is done once the user authenticates, activates access to additional applications, or as soon as applications scale out and involve more servers. The described proof-of-concept implementation explores, to what degree an agent-less BYOD solution, based only on SDN, can lower the attack surface by explicit user opt-ins for particular services. Further, an assessment of the number of required rules within the flow tables of switches completes this work.}, address = {Würzburg, Germany}, author = {Gebert, Steffen and Zinner, Thomas and Gray, Nicholas and Durner, Raphael and Lorenz, Class and Lange, Stanislav}, booktitle = {28th International Teletraffic Congress (ITC 28)}, month = 9, title = {Demonstrating a Personalized Secure-By-Default Bring Your Own Device Solution Based on Software Defined Networking}, year = 2016 }
• Roth, D., Waldow, K., Stetter, F., Bente, G., Latoschik, M.E., Fuhrmann, A.: SIAMC - A Socially Immersive Avatar Mediated Communication Platform. In: Kranzlmüller, D. und Klinker, G. (hrsg.) Proceedings of the 22nd ACM Conference on Virtual Reality Software and Technology, VRST 2016, Munich, Germany, 2-4 November. S. 357-358. ACM (2016).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  In this paper, we present a avatar-mediated communication plat- form for socially immersive interaction in virtual reality (VR). Our approach is based on the combination of body tracking, facial ex- pression tracking and ”fishtank” VR. Our prototype enables two remote users to communicate via avatars.
  @conference{roth2016siamc, abstract = {In this paper, we present a avatar-mediated communication plat- form for socially immersive interaction in virtual reality (VR). Our approach is based on the combination of body tracking, facial ex- pression tracking and ”fishtank” VR. Our prototype enables two remote users to communicate via avatars.}, author = {Roth, Daniel and Waldow, Kristoffer and Stetter, Felix and Bente, Gary and Latoschik, Marc Erich and Fuhrmann, Arnulph}, booktitle = {Proceedings of the 22nd ACM Conference on Virtual Reality Software and Technology, VRST 2016, Munich, Germany, 2-4 November}, crossref = {conf/vrst/2016}, editor = {Kranzlmüller, Dieter and Klinker, Gudrun}, pages = {357-358}, publisher = {ACM}, title = {SIAMC - A Socially Immersive Avatar Mediated Communication Platform}, year = 2016 }
• Budig, B., van Dijk, T.C., Kirchner, F.: Glyph Miner: A System for Efficiently Extracting Glyphs from Early Prints in the Context of OCR. In: Adam, N.R., Cassel, L. (B.), Yesha, Y., Furuta, R., und Weigle, M.C. (hrsg.) Proceedings of the 16th ACM/IEEE-CS on Joint Conference on Digital Libraries. S. 31--34. ACM (2016).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  While off-the-shelf OCR systems work well on many modern documents, the heterogeneity of early prints provides a significant challenge. To achieve good recognition quality, existing software must be "trained" specifically to each particular corpus. This is a tedious process that involves significant user effort. In this paper we demonstrate a system that generically replaces a common part of the training pipeline with a more efficient workflow: Given a set of scanned pages of a historical document, our system uses an efficient user interaction to semi-automatically extract large numbers of occurrences of glyphs indicated by the user. In a preliminary case study, we evaluate the effectiveness of our approach by embedding our system into the workflow at the University Library Würzburg.
  @inproceedings{conf/jcdl/BudigDK16, abstract = {While off-the-shelf OCR systems work well on many modern documents, the heterogeneity of early prints provides a significant challenge. To achieve good recognition quality, existing software must be "trained" specifically to each particular corpus. This is a tedious process that involves significant user effort. In this paper we demonstrate a system that generically replaces a common part of the training pipeline with a more efficient workflow: Given a set of scanned pages of a historical document, our system uses an efficient user interaction to semi-automatically extract large numbers of occurrences of glyphs indicated by the user. In a preliminary case study, we evaluate the effectiveness of our approach by embedding our system into the workflow at the University Library Würzburg.}, author = {Budig, Benedikt and van Dijk, Thomas C. and Kirchner, Felix}, booktitle = {Proceedings of the 16th ACM/IEEE-CS on Joint Conference on Digital Libraries}, crossref = {conf/jcdl/2016}, editor = {Adam, Nabil R. and Cassel, Lillian (Boots) and Yesha, Yelena and Furuta, Richard and Weigle, Michele C.}, pages = {31--34}, publisher = {ACM}, series = {JCDL '16}, title = {Glyph Miner: A System for Efficiently Extracting Glyphs from Early Prints in the Context of OCR.}, year = 2016 }
• Münster, S., Niebling, F.: Building a Wiki resource on visual knowledge related knowledge assets. In: Spender, J.C., Noennig, J.R., und Schiuma, G. (hrsg.) Towards a new Architecture of Knowledge: Big Data, Culture, Creativity. Arts for Business Ltd, University of Basilicata (2016).
  [ BibTeX ]
   
  @inproceedings{munster2016building, address = {University of Basilicata}, author = {Münster, Sander and Niebling, Florian}, booktitle = {Towards a new Architecture of Knowledge: Big Data, Culture, Creativity}, editor = {Spender, J.C. and Noennig, Jörg Rainer and Schiuma, Giovanni}, month = 6, publisher = {Arts for Business Ltd}, series = {International Forum on Knowledge Asset Dynamics}, title = {Building a Wiki resource on visual knowledge related knowledge assets}, year = 2016 }
• Ott, S.: Browser-based Measurement of HTTP Live Streaming Performance during the Olympic Games 2016, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-praktikum-2016-9, author = {Ott, Stefan}, month = 12, school = {University of Würzburg}, title = {Browser-based Measurement of HTTP Live Streaming Performance during the Olympic Games 2016}, year = 2016 }
• Fischer, V.: Emulation Framework for the Subjective Evaluation of Delays in Web and Business Applications, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2016-3, author = {Fischer, Valentin}, month = 3, school = {University of Würzburg}, title = {Emulation Framework for the Subjective Evaluation of Delays in Web and Business Applications}, year = 2016 }
• Ott, M.: Performance Evaluation of Caching Architectures using the Internet Proxy Squid, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2016-3, author = {Ott, Michael}, month = 3, school = {University of Würzburg}, title = {Performance Evaluation of Caching Architectures using the Internet Proxy Squid}, year = 2016 }
• Scholz, M.: Einflussnahme zeitlicher und sozialer Muster auf die Effizienz von Caching, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2016-2, author = {Scholz, Martin}, month = 3, school = {University of Würzburg}, title = {Einflussnahme zeitlicher und sozialer Muster auf die Effizienz von Caching}, year = 2016 }
• Gebert, S., Zinner, T., Lange, S., Schwartz, C., Tran-Gia, P.: Discrete-Time Analysis: Deriving the Distribution of the Number of Events in an Arbitrarily Distributed Interval. (2016).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  For the context of discrete-time analysis, this document describes how to derive the distribution of the number of events in an arbitrarily distributed interval.
  @techreport{gebert2016discretetime, abstract = {For the context of discrete-time analysis, this document describes how to derive the distribution of the number of events in an arbitrarily distributed interval.}, author = {Gebert, Steffen and Zinner, Thomas and Lange, Stanislav and Schwartz, Christian and Tran-Gia, Phuoc}, month = {Juni}, number = 498, title = {Discrete-Time Analysis: Deriving the Distribution of the Number of Events in an Arbitrarily Distributed Interval}, year = 2016 }
• Wamser, F., Casas, P., Seufert, M., Moldovan, C., Tran-Gia, P., Hoßfeld, T.: Modeling the YouTube Stack: from Packets to Quality of Experience. Computer Networks. 109, 211-224 (2016).
  [ Abstract ] [ BibTeX ]
   
  YouTube is one of the most popular and volume-dominant services in today’s Internet, and has changed the Web for ever. Consequently, network operators are forced to consider it in the design, deployment, and optimization of their networks. Taming YouTube requires a good understanding of the complete YouTube stack, from the network streaming service to the application itself. Understanding the interplays between individual YouTube functionalities and their implications for traffic and user Quality of Experience (QoE) becomes paramount nowadays. In this paper we characterize and model the YouTube stack at different layers, going from the generated network traffic to the QoE perceived by the users watching YouTube videos. Firstly, we present a network traffic model for the YouTube flow control mechanism, which permits to understand how YouTube provisions video traffic flows to users. Secondly, we investigate how traffic is consumed at the client side, deriving a simple model for the YouTube application. Thirdly, we analyze the implications for the end user, and present a model for the quality as perceived by them. This model is finally integrated into a system for real time QoE-based YouTube monitoring, highly useful to operators to assess the performance of their networks for provisioning YouTube videos. The central parameter for all the presented models is the buffer level at the YouTube application layer. This paper provides an extensive compendium of objective tools and models for network operators to better understand the YouTube traffic in their networks, to predict the playback behavior of the video player, and to assess how well they do it in the practice with the satisfaction of their customers watching YouTube.
  @article{info3-article-2016-6, abstract = {YouTube is one of the most popular and volume-dominant services in today’s Internet, and has changed the Web for ever. Consequently, network operators are forced to consider it in the design, deployment, and optimization of their networks. Taming YouTube requires a good understanding of the complete YouTube stack, from the network streaming service to the application itself. Understanding the interplays between individual YouTube functionalities and their implications for traffic and user Quality of Experience (QoE) becomes paramount nowadays. In this paper we characterize and model the YouTube stack at different layers, going from the generated network traffic to the QoE perceived by the users watching YouTube videos. Firstly, we present a network traffic model for the YouTube flow control mechanism, which permits to understand how YouTube provisions video traffic flows to users. Secondly, we investigate how traffic is consumed at the client side, deriving a simple model for the YouTube application. Thirdly, we analyze the implications for the end user, and present a model for the quality as perceived by them. This model is finally integrated into a system for real time QoE-based YouTube monitoring, highly useful to operators to assess the performance of their networks for provisioning YouTube videos. The central parameter for all the presented models is the buffer level at the YouTube application layer. This paper provides an extensive compendium of objective tools and models for network operators to better understand the YouTube traffic in their networks, to predict the playback behavior of the video player, and to assess how well they do it in the practice with the satisfaction of their customers watching YouTube.}, author = {Wamser, Florian and Casas, Pedro and Seufert, Michael and Moldovan, Christian and Tran-Gia, Phuoc and Hoßfeld, Tobias}, journal = {Computer Networks}, month = 11, number = 2, pages = {211-224}, title = {Modeling the YouTube Stack: from Packets to Quality of Experience}, volume = 109, year = 2016 }
• Schwind, A.: WhatsAnalyzer: a Tool for Collecting and Analyzing WhatsApp Chats, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-praktikum-2016-1, author = {Schwind, Anika}, month = 3, school = {University of Wuerzburg}, title = {WhatsAnalyzer: a Tool for Collecting and Analyzing WhatsApp Chats}, year = 2016 }
• Wamser, F., Seufert, M., Höfner, S., Tran-Gia, P.: Concept for Client-initiated Selection of Cloud Instances for Improving QoE of Distributed Cloud Services. ACM SIGCOMM Workshop on QoE-based Analysis and Management of Data Communication Networks (Internet-QoE). , Florianópolis, Brazil (2016).
  [ Abstract ] [ BibTeX ]
   
  We introduce a concept for client-initiated selection of service location and service quality for improving the Quality of Experience (QoE) of general cloud services. It is loosely based on the HTTP adaptive streaming approach (e.g., MPEG DASH). A manifest file compiled by the cloud service provider specifies the available service locations and qualities, from which the user selects the optimal service instance based on contextual information obtained from client measurements and user preferences. The proposed concept is defined and is implemented in two client-based decision algorithms for improving the QoE of a simple picture gallery cloud service. These decision algorithms are evaluated and their impact on the service delivery is discussed. The evaluation shows that it is possible to improve the service location and quality selection by light-weight client-based algorithms.
  @inproceedings{info3-inproceedings-2016-14, abstract = {We introduce a concept for client-initiated selection of service location and service quality for improving the Quality of Experience (QoE) of general cloud services. It is loosely based on the HTTP adaptive streaming approach (e.g., MPEG DASH). A manifest file compiled by the cloud service provider specifies the available service locations and qualities, from which the user selects the optimal service instance based on contextual information obtained from client measurements and user preferences. The proposed concept is defined and is implemented in two client-based decision algorithms for improving the QoE of a simple picture gallery cloud service. These decision algorithms are evaluated and their impact on the service delivery is discussed. The evaluation shows that it is possible to improve the service location and quality selection by light-weight client-based algorithms.}, address = {Florianópolis, Brazil}, author = {Wamser, Florian and Seufert, Michael and Höfner, Steffen and Tran-Gia, Phuoc}, booktitle = {ACM SIGCOMM Workshop on QoE-based Analysis and Management of Data Communication Networks (Internet-QoE)}, month = 8, title = {Concept for Client-initiated Selection of Cloud Instances for Improving QoE of Distributed Cloud Services}, year = 2016 }
• Ernst, F.: Einfluss von Netzwerkparamtern auf Synchronisationsmechanismen in Videospielen, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2016-4, author = {Ernst, Felix}, month = 5, school = {University of Würzburg}, title = {Einfluss von Netzwerkparamtern auf Synchronisationsmechanismen in Videospielen}, year = 2016 }
• Gebert, S., Zinner, T., Lange, S., Schwartz, C., Tran-Gia, P.: Discrete-Time Analysis: Deriving the Distribution of the Number of Events in an Arbitrarily Distributed Interval. University of Wuerzburg (2016).
  [ BibTeX ]
   
  @techreport{info3-techreport-2016-1, author = {Gebert, Steffen and Zinner, Thomas and Lange, Stanislav and Schwartz, Christian and Tran-Gia, Phuoc}, institution = {University of Wuerzburg}, month = 6, number = 498, title = {Discrete-Time Analysis: Deriving the Distribution of the Number of Events in an Arbitrarily Distributed Interval}, year = 2016 }
• Seufert, M.: Application-Layer Monitoring of QoE Parameters for Mobile YouTube Video Streaming in the Field. , IEEE 6th International Conference on Communications and Electronics (ICCE), Ha Long, Vietnam (2016).
  [ BibTeX ]
   
  @presentation{info3-presentation-2016-5, address = {IEEE 6th International Conference on Communications and Electronics (ICCE), Ha Long, Vietnam}, author = {Seufert, Michael}, month = 7, title = {Application-Layer Monitoring of QoE Parameters for Mobile YouTube Video Streaming in the Field}, year = 2016 }
• Doerfel, S., Zoller, D., Singer, P., Niebler, T., Hotho, A., Strohmaier, M.: What Users Actually do in a Social Tagging System: A Study of User Behavior in BibSonomy. ACM Transactions on the Web. 10, 14:1--14:32 (2016).
  [ Abstract ] [ BibTeX ] [ URL ] [ DOI ]
   
  Social tagging systems have established themselves as an important part in today’s web and have attracted the interest of our research community in a variety of investigations. Henceforth, several aspects of social tagging systems have been discussed and assumptions have emerged on which our community builds their work. Yet, testing such assumptions has been difficult due to the absence of suitable usage data in the past. In this work, we thoroughly investigate and evaluate four aspects about tagging systems, covering social interaction, retrieval of posted resources, the importance of the three different types of entities, users, resources, and tags, as well as connections between these entities’ popularity in posted and in requested content. For that purpose, we examine live server log data gathered from the real-world, public social tagging system BibSonomy. Our empirical results paint a mixed picture about the four aspects. While for some, typical assumptions hold to a certain extent, other aspects need to be reflected in a very critical light. Our observations have implications for the understanding of social tagging systems, and the way they are used on the web. We make the dataset used in this work available to other researchers.
  @article{doerfel2016users, abstract = {Social tagging systems have established themselves as an important part in today’s web and have attracted the interest of our research community in a variety of investigations. Henceforth, several aspects of social tagging systems have been discussed and assumptions have emerged on which our community builds their work. Yet, testing such assumptions has been difficult due to the absence of suitable usage data in the past. In this work, we thoroughly investigate and evaluate four aspects about tagging systems, covering social interaction, retrieval of posted resources, the importance of the three different types of entities, users, resources, and tags, as well as connections between these entities’ popularity in posted and in requested content. For that purpose, we examine live server log data gathered from the real-world, public social tagging system BibSonomy. Our empirical results paint a mixed picture about the four aspects. While for some, typical assumptions hold to a certain extent, other aspects need to be reflected in a very critical light. Our observations have implications for the understanding of social tagging systems, and the way they are used on the web. We make the dataset used in this work available to other researchers.}, author = {Doerfel, Stephan and Zoller, Daniel and Singer, Philipp and Niebler, Thomas and Hotho, Andreas and Strohmaier, Markus}, journal = {ACM Transactions on the Web}, month = {may}, number = 2, pages = {14:1--14:32}, publisher = {ACM}, title = {What Users Actually do in a Social Tagging System: A Study of User Behavior in BibSonomy}, volume = 10, year = 2016 }
• Hettinger, L., Jannidis, F., Reger, I., Hotho, A.: Classification of Literary Subgenres. DHd 2016 (2016).
  [ BibTeX ]
   
  @inproceedings{hettinger2016classification, author = {Hettinger, Lena and Jannidis, Fotis and Reger, Isabella and Hotho, Andreas}, booktitle = {DHd 2016}, title = {Classification of Literary Subgenres}, year = 2016 }
• Furth, S., Baumeister, J.: Semantification of Large Corpora of Technical Documentation. In: Atzmueller, M., Oussena, S., und Roth-Berghofer, T. (hrsg.) Enterprise Big Data Engineering, Analytics, and Management. IGI Global (2016).
  [ BibTeX ] [ URL ]
   
  @inproceedings{furth2016semantification, author = {Furth, Sebastian and Baumeister, Joachim}, booktitle = {Enterprise Big Data Engineering, Analytics, and Management}, editor = {Atzmueller, Martin and Oussena, Samia and Roth-Berghofer, Thomas}, publisher = {IGI Global}, title = {Semantification of Large Corpora of Technical Documentation}, type = {Publication}, year = 2016 }
• Landbeck, D.: Framework for Simulative Performance Evaluation of HTTP Adaptive Video Streaming, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2016-2, author = {Landbeck, Demian}, month = 3, school = {University of Wuerzburg}, title = {Framework for Simulative Performance Evaluation of HTTP Adaptive Video Streaming}, year = 2016 }
• Baumeister, J., Striffler, A., Brandt, M., Neumann, M.: Collaborative Decision Support and Documentation in Chemical Safety with KnowSEC. Journal of Cheminformatics. 8, 1-16 (2016).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  To protect the health of human and environment, the European Union implemented the REACH regulation for chemical substances. REACH is an acronym for Registration, Evaluation, Authorization, and Restriction of Chemicals. Under REACH, the authorities have the task of assessing chemical substances, especially those that might pose a risk to human health or environment. The work under REACH is scientifically, technically and procedurally a complex and knowledge-intensive task that is jointly performed by the European Chemicals Agency and member state authorities in Europe. The assessment of substances under REACH conducted in the German Environment Agency is supported by the knowledge-based system KnowSEC, which is used for the screening, documentation, and decision support when working on chemical substances. The software KnowSEC integrates advanced semantic technologies and strong problem solving methods. It allows for the collaborative work on substances in the context of the European REACH regulation. We discuss the applied methods and process models and we report on experiences with the implementation and use of the system.
  @article{baumeister2016collaborative, abstract = {To protect the health of human and environment, the European Union implemented the REACH regulation for chemical substances. REACH is an acronym for Registration, Evaluation, Authorization, and Restriction of Chemicals. Under REACH, the authorities have the task of assessing chemical substances, especially those that might pose a risk to human health or environment. The work under REACH is scientifically, technically and procedurally a complex and knowledge-intensive task that is jointly performed by the European Chemicals Agency and member state authorities in Europe. The assessment of substances under REACH conducted in the German Environment Agency is supported by the knowledge-based system KnowSEC, which is used for the screening, documentation, and decision support when working on chemical substances. The software KnowSEC integrates advanced semantic technologies and strong problem solving methods. It allows for the collaborative work on substances in the context of the European REACH regulation. We discuss the applied methods and process models and we report on experiences with the implementation and use of the system.}, author = {Baumeister, Joachim and Striffler, Albrecht and Brandt, Marc and Neumann, Michael}, journal = {Journal of Cheminformatics}, number = 21, pages = {1-16}, title = {Collaborative Decision Support and Documentation in Chemical Safety with KnowSEC}, volume = 8, year = 2016 }
• Seufert, M.: Research Activities Report for "Crowdsourcing TF" and "Managing Web & Cloud QoE TF". , 10th Qualinet General Meeting, Lisbon, Portugal (2016).
  [ BibTeX ]
   
  @presentation{info3-presentation-2016-4, address = {10th Qualinet General Meeting, Lisbon, Portugal}, author = {Seufert, Michael}, month = 6, title = {Research Activities Report for "Crowdsourcing TF" and "Managing Web & Cloud QoE TF"}, year = 2016 }
• Schwartz, C.: Modeling and Evaluation of Multi-Stakeholder Scenarios in Communication Networks, (2016).
  [ BibTeX ]
   
  @phdthesis{info3-dissertation-2016-1, author = {Schwartz, Christian}, month = 4, school = {University of Wuerzburg}, title = {Modeling and Evaluation of Multi-Stakeholder Scenarios in Communication Networks}, year = 2016 }
• Chaplick, S., Fleszar, K., Lipp, F., Ravsky, A., Verbitsky, O., Wolff, A.: The Complexity of Drawing Graphs on Few Lines and Few Planes, http://arxiv.org/abs/1607.06444, (2016).
  [ BibTeX ] [ URL ]
   
  @misc{cflrvw-cdgfl-arXiv16, author = {Chaplick, Steven and Fleszar, Krzysztof and Lipp, Fabian and Ravsky, Alexander and Verbitsky, Oleg and Wolff, Alexander}, howpublished = {Arxiv report}, month = {jun}, note = {Available at http://arxiv.org/abs/1607.06444}, title = {The Complexity of Drawing Graphs on Few Lines and Few Planes}, year = 2016 }
• Seufert, M., Burger, V., Lorey, K., Seith, A., Loh, F., Tran-Gia, P.: Assessment of Subjective Influence and Trust with an Online Social Network Game. Computers in Human Behavior. 64, 233-246 (2016).
  [ Abstract ] [ BibTeX ]
   
  The deduction of influence and trust between two individuals only from objective data in online social networks (OSNs) is a rather vague approach. Subjective assessments via surveys produce better results, but are harder to conduct considering the vast amount of friendships of OSN users. This work presents a framework for personalized surveys on relationships in OSNs, which follows a gamification approach. A Facebook game was developed, which was used to subjectively assess social influence and interpersonal trust based on models from psychology. The results show that it is possible to obtain subjective opinions and (limited) objective data about relationships with an OSN game. Also an implicit assessment of influence and trust with subcategory questions is feasible in this case.
  @article{info3-article-2016-7, abstract = {The deduction of influence and trust between two individuals only from objective data in online social networks (OSNs) is a rather vague approach. Subjective assessments via surveys produce better results, but are harder to conduct considering the vast amount of friendships of OSN users. This work presents a framework for personalized surveys on relationships in OSNs, which follows a gamification approach. A Facebook game was developed, which was used to subjectively assess social influence and interpersonal trust based on models from psychology. The results show that it is possible to obtain subjective opinions and (limited) objective data about relationships with an OSN game. Also an implicit assessment of influence and trust with subcategory questions is feasible in this case.}, author = {Seufert, Michael and Burger, Valentin and Lorey, Karl and Seith, Alexander and Loh, Frank and Tran-Gia, Phuoc}, journal = {Computers in Human Behavior}, month = 11, pages = {233-246}, title = {Assessment of Subjective Influence and Trust with an Online Social Network Game}, volume = 64, year = 2016 }
• Metter, C., Seufert, M., Wamser, F., Zinner, T., Tran-Gia, P.: Analytic Model for SDN Controller Traffic and Switch Table Occupancy. 12th International Conference on Network and Service Management (CNSM). , Best Paper Award, Montreal, Canada (2016).
  [ Abstract ] [ BibTeX ]
   
  Software Defined Networking (SDN) is a major paradigm in the field of current communication networks. SDN is used as the basis of many new networks although few performance models are available in the literature, and the majority of performance evaluations are based primarily on practical measurements. To fill this gap, we develop an analytical model to assess SDN control plane traffic as well as the occupancy of the flow table of an SDN switch. The contribution of this work is the formulation of the model for the performance-decisive parameters control-plane traffic and flow table occupancy and the application of the model for different data plane traffic characteristics. In the end, there is a discussion about the setting of time-out values for storing flow entries in the switch flow table depending on the traffic characteristics in the data plane. The trade-off between the signaling traffic in the control plane and the occupancy of the flow table is discussed in order to minimize both.
  @inproceedings{info3-inproceedings-2016-17, abstract = {Software Defined Networking (SDN) is a major paradigm in the field of current communication networks. SDN is used as the basis of many new networks although few performance models are available in the literature, and the majority of performance evaluations are based primarily on practical measurements. To fill this gap, we develop an analytical model to assess SDN control plane traffic as well as the occupancy of the flow table of an SDN switch. The contribution of this work is the formulation of the model for the performance-decisive parameters control-plane traffic and flow table occupancy and the application of the model for different data plane traffic characteristics. In the end, there is a discussion about the setting of time-out values for storing flow entries in the switch flow table depending on the traffic characteristics in the data plane. The trade-off between the signaling traffic in the control plane and the occupancy of the flow table is discussed in order to minimize both.}, address = {Best Paper Award, Montreal, Canada}, author = {Metter, Christopher and Seufert, Michael and Wamser, Florian and Zinner, Thomas and Tran-Gia, Phuoc}, booktitle = {12th International Conference on Network and Service Management (CNSM)}, month = 10, title = {Analytic Model for SDN Controller Traffic and Switch Table Occupancy}, year = 2016 }
• Lipp, F., Wolff, A., Zink, J.: Faster Force-Directed Graph Drawing with the Well-Separated Pair Decomposition. Algorithms. 9, 53 (2016).
  [ Abstract ] [ BibTeX ] [ URL ] [ DOI ]
   
  The force-directed paradigm is one of the few generic approaches to drawing graphs. Since force-directed algorithms can be extended easily, they are used frequently. Most of these algorithms are, however, quite slow on large graphs, as they compute a quadratic number of forces in each iteration. We give a new algorithm that takes only O ( m + n log n ) time per iteration when laying out a graph with n vertices and m edges. Our algorithm approximates the true forces using the so-called well-separated pair decomposition. We perform experiments on a large number of graphs and show that we can strongly reduce the runtime, even on graphs with less than a hundred vertices, without a significant influence on the quality of the drawings (in terms of the number of crossings and deviation in edge lengths).
  @article{lwz-ffdgd-algorithms16, abstract = {The force-directed paradigm is one of the few generic approaches to drawing graphs. Since force-directed algorithms can be extended easily, they are used frequently. Most of these algorithms are, however, quite slow on large graphs, as they compute a quadratic number of forces in each iteration. We give a new algorithm that takes only O ( m + n log n ) time per iteration when laying out a graph with n vertices and m edges. Our algorithm approximates the true forces using the so-called well-separated pair decomposition. We perform experiments on a large number of graphs and show that we can strongly reduce the runtime, even on graphs with less than a hundred vertices, without a significant influence on the quality of the drawings (in terms of the number of crossings and deviation in edge lengths).}, author = {Lipp, Fabian and Wolff, Alexander and Zink, Johannes}, journal = {Algorithms}, number = 3, pages = 53, title = {Faster Force-Directed Graph Drawing with the Well-Separated Pair Decomposition}, volume = 9, year = 2016 }
• Borchert, K., Hirth, M., Zinner, T., Mocanu, D.C.: Correlating QoE and Technical Parameters of an SAP System in an Enterprise Environment. QCMan IEEE Workshop on QoE centric Management (2016).
  [ BibTeX ]
   
  @inproceedings{info3-inproceedings-2016-15, author = {Borchert, Kathrin and Hirth, Matthias and Zinner, Thomas and Mocanu, Decebal Constantin}, booktitle = {QCMan IEEE Workshop on QoE centric Management}, month = 9, title = {Correlating QoE and Technical Parameters of an SAP System in an Enterprise Environment}, year = 2016 }
• Knapp, T.: Assessment of the ONOS SDN Controller in Case of Network Errors, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2016-6, author = {Knapp, Tobias}, month = 12, school = {University of Wuerzburg}, title = {Assessment of the ONOS SDN Controller in Case of Network Errors}, year = 2016 }
• Müssig, A.: Comparison of State Synchronization Strategies for a Cloud-based Firewall VNF, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2016-4, author = {Müssig, Alexander}, month = 9, school = {Universität Würzburg}, title = {Comparison of State Synchronization Strategies for a Cloud-based Firewall VNF}, year = 2016 }
• Berani, S.: Evaluation of an Adaptive Flow Monitoring Implementation for SDN-based Networks, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2016-5, author = {Berani, Shpend}, month = 9, school = {Universität Würzburg}, title = {Evaluation of an Adaptive Flow Monitoring Implementation for SDN-based Networks}, year = 2016 }
• Dallmann, A., Niebler, T., Lemmerich, F., Hotho, A.: Extracting Semantics from Random Walks on Wikipedia: Comparing learning and counting methods. In: West, R., Zia, L., Taraborelli, D., und Leskovec, J. (hrsg.) Wiki Workshop@ICWSM (2016).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  Semantic relatedness between words has been extracted from a variety of sources. In this ongoing work, we explore and compare several options for determining if semantic relatedness can be extracted from navigation structures in Wikipedia. In that direction, we first investigate the potential of representation learning techniques such as DeepWalk in comparison to previously applied methods based on counting co-occurrences. Since both methods are based on (random) paths in the network, we also study different approaches to generate paths from Wikipedia link structure. For this task, we do not only consider the link structure of Wikipedia, but also actual navigation behavior of users. Finally, we analyze if semantics can also be extracted from smaller subsets of the Wikipedia link network. As a result we find that representa- tion learning techniques mostly outperform the investigated co-occurrence counting methods on the Wikipedia network. However, we find that this is not the case for paths sampled from human navigation behavior.
  @inproceedings{dallmann2016extracting, abstract = {Semantic relatedness between words has been extracted from a variety of sources. In this ongoing work, we explore and compare several options for determining if semantic relatedness can be extracted from navigation structures in Wikipedia. In that direction, we first investigate the potential of representation learning techniques such as DeepWalk in comparison to previously applied methods based on counting co-occurrences. Since both methods are based on (random) paths in the network, we also study different approaches to generate paths from Wikipedia link structure. For this task, we do not only consider the link structure of Wikipedia, but also actual navigation behavior of users. Finally, we analyze if semantics can also be extracted from smaller subsets of the Wikipedia link network. As a result we find that representa- tion learning techniques mostly outperform the investigated co-occurrence counting methods on the Wikipedia network. However, we find that this is not the case for paths sampled from human navigation behavior.}, author = {Dallmann, Alexander and Niebler, Thomas and Lemmerich, Florian and Hotho, Andreas}, booktitle = {Wiki Workshop@ICWSM}, editor = {West, Robert and Zia, Leila and Taraborelli, Dario and Leskovec, Jure}, title = {Extracting Semantics from Random Walks on Wikipedia: Comparing learning and counting methods}, year = 2016 }
• Dinh-Xuan, L., Seufert, M., Wamser, F., Tran-Gia, P.: QoE Aware Placement of Content in Edge Networks on the Example of a Photo Album Cloud Service. IEEE 6th International Conference on Communications and Electronics (ICCE). , Ha Long, Vietnam (2016).
  [ Abstract ] [ BibTeX ]
   
  The paradigm of Software as a Service has gained great achievements in the last decade. By transferring computation and storage to the cloud and migrating services to the edge network, users benefit from using demanding services on lightweight devices. However, the user perceived quality of experience (QoE) for these services is facing the challenges of network impairments and the accessibility of users. Unlike a typical PC-based software, the cloud provides users a location-aware, flexible placement of resource for a cost effective service. The geographical placement of content is therefore one of the key factors that affects the user's satisfaction. The closer the content to the user geographically is, the faster it will be delivered to the user that will also increase the user perceived QoE. In this work, we estimate more precisely the QoE for photo loading time in a particular usage of a photo album cloud service with regard to the influence of various parameters. Firstly, we validate a TCP throughput model and use it to calculate the photo loading time from a given photo size and network QoS. Thereafter, we formulate a mapping function to calculate the MOS value from a QoE model adding the output of the TCP model. From this mapping function, we can estimate QoE for photo loading time from a given photo size, its placement and network QoS. Our main contribution is to determine the trade-off between the size of photo and its placement to acquire a high QoE for photo loading time, which is important for the development of a photo album cloud service.
  @inproceedings{info3-inproceedings-2016-16, abstract = {The paradigm of Software as a Service has gained great achievements in the last decade. By transferring computation and storage to the cloud and migrating services to the edge network, users benefit from using demanding services on lightweight devices. However, the user perceived quality of experience (QoE) for these services is facing the challenges of network impairments and the accessibility of users. Unlike a typical PC-based software, the cloud provides users a location-aware, flexible placement of resource for a cost effective service. The geographical placement of content is therefore one of the key factors that affects the user's satisfaction. The closer the content to the user geographically is, the faster it will be delivered to the user that will also increase the user perceived QoE. In this work, we estimate more precisely the QoE for photo loading time in a particular usage of a photo album cloud service with regard to the influence of various parameters. Firstly, we validate a TCP throughput model and use it to calculate the photo loading time from a given photo size and network QoS. Thereafter, we formulate a mapping function to calculate the MOS value from a QoE model adding the output of the TCP model. From this mapping function, we can estimate QoE for photo loading time from a given photo size, its placement and network QoS. Our main contribution is to determine the trade-off between the size of photo and its placement to acquire a high QoE for photo loading time, which is important for the development of a photo album cloud service.}, address = {Ha Long, Vietnam}, author = {Dinh-Xuan, Lam and Seufert, Michael and Wamser, Florian and Tran-Gia, Phuoc}, booktitle = {IEEE 6th International Conference on Communications and Electronics (ICCE)}, month = 7, title = {QoE Aware Placement of Content in Edge Networks on the Example of a Photo Album Cloud Service}, year = 2016 }
• Wamser, F.: Leistungsbewertung von Ressourcenmanagementstrategien für zelluläre und drahtlose Mesh-Netzwerke. Lecture Notes in Informatics (LNI). Ausgezeichnete Informatikdissertationen 2015, (2016).
  [ Abstract ] [ BibTeX ]
   
  Heutige Kommunikationsnetzwerke müssen eine große Anzahl an heterogenen Anwendungen und Diensten schultern. Dies gilt zusätzlich zu den Herausforderungen, dass sie kostengünstig sein sollen und schnelles, qualitativ-hochwertiges Internet anbieten müssen. Ein spezialisiertes Ressourcenmanagement kann in vielen dieser Fälle helfen und kann eine Win-Win-Situation für beide Parteien - den Benutzer und das Netzwerk - darstellen. In meiner Dissertation untersuche ich verschiedene neue Ressourcenmanagementansätze zur Leistungsoptimierung und Steigerung der Ressourceneffizienz in Zugangsnetzen. Die untersuchten Ansätze arbeiten auf verschiedenen Kommunikationsschichten und erfüllen unterschiedliche Ziele. Am Ende stellt diese Arbeit Empfehlungen für Netzbetreiber dar, wie ein Ressourcenmanagement für unterschiedliche Netzwerktypen und Ziele aussehen kann und welcher Nutzen in Vergleich mit dem erforderlichen Aufwand und der höheren Komplexität zu erwarten ist.
  @article{info3-article-2016-8, abstract = {Heutige Kommunikationsnetzwerke müssen eine große Anzahl an heterogenen Anwendungen und Diensten schultern. Dies gilt zusätzlich zu den Herausforderungen, dass sie kostengünstig sein sollen und schnelles, qualitativ-hochwertiges Internet anbieten müssen. Ein spezialisiertes Ressourcenmanagement kann in vielen dieser Fälle helfen und kann eine Win-Win-Situation für beide Parteien - den Benutzer und das Netzwerk - darstellen. In meiner Dissertation untersuche ich verschiedene neue Ressourcenmanagementansätze zur Leistungsoptimierung und Steigerung der Ressourceneffizienz in Zugangsnetzen. Die untersuchten Ansätze arbeiten auf verschiedenen Kommunikationsschichten und erfüllen unterschiedliche Ziele. Am Ende stellt diese Arbeit Empfehlungen für Netzbetreiber dar, wie ein Ressourcenmanagement für unterschiedliche Netzwerktypen und Ziele aussehen kann und welcher Nutzen in Vergleich mit dem erforderlichen Aufwand und der höheren Komplexität zu erwarten ist.}, author = {Wamser, Florian}, journal = {Lecture Notes in Informatics (LNI)}, title = {Leistungsbewertung von Ressourcenmanagementstrategien für zelluläre und drahtlose Mesh-Netzwerke}, volume = {Ausgezeichnete Informatikdissertationen 2015}, year = 2016 }
• Zinner, T., Hirth, M., Fischer, V., Hohlfeld, O.: ERWIN - Enabling the Reproducible Investigation of WaItiNg Times for Arbitrary Workflows. 8th International Conference on Quality of Multimedia Experiene (QoMEX). , Lisbon, Portugal (2016).
  [ Abstract ] [ BibTeX ]
   
  Delay effects can impact the Quality of Experience of interactive systems, which motivates research assessing delay impairments, mostly for web based systems. Current studies follow individual methodologies and typically assesses individual and custom-made web pages, whose construction requires expert knowledge in web technologies. A range of native, non-web applications cannot be easily modified for delay studies. Thus, a generalized methodology for assessing delay impacts for a broad range of applications that is assessable to researchers without (web) development expertise is still missing. This paper con- tributes to this open problem by i) presenting a new methodology for reproducible delay assessments in a broad class of (web-based) systems and ii) presenting an open-source implementation to be used by the community. This methodology particularly aims at making delay assessment available to a broad range of researchers by avoiding programming skills and thus by lowering the barrier for setting-up delay assessments.
  @inproceedings{info3-inproceedings-2016-6, abstract = {Delay effects can impact the Quality of Experience of interactive systems, which motivates research assessing delay impairments, mostly for web based systems. Current studies follow individual methodologies and typically assesses individual and custom-made web pages, whose construction requires expert knowledge in web technologies. A range of native, non-web applications cannot be easily modified for delay studies. Thus, a generalized methodology for assessing delay impacts for a broad range of applications that is assessable to researchers without (web) development expertise is still missing. This paper con- tributes to this open problem by i) presenting a new methodology for reproducible delay assessments in a broad class of (web-based) systems and ii) presenting an open-source implementation to be used by the community. This methodology particularly aims at making delay assessment available to a broad range of researchers by avoiding programming skills and thus by lowering the barrier for setting-up delay assessments.}, address = {Lisbon, Portugal}, author = {Zinner, Thomas and Hirth, Matthias and Fischer, Valentin and Hohlfeld, Oliver}, booktitle = {8th International Conference on Quality of Multimedia Experiene (QoMEX)}, month = 6, title = {ERWIN - Enabling the Reproducible Investigation of WaItiNg Times for Arbitrary Workflows}, year = 2016 }
• Gebert, S., Zinner, T., Lange, S., Schwartz, C., Tran-Gia, P.: Performance Modeling of Softwarized Network Functions Using Discrete-Time Analysis. 28th International Teletraffic Congress (ITC). , Würzburg, Germany (2016).
  [ Abstract ] [ BibTeX ]
   
  The softwarization of networks promises cost savings and better scalability of network functions by moving functionality from specialized devices into commercial off-the-shelf hardware. Generalized computing hardware offers many degrees for adjustment and tuning, which can affect performance and resource utilization. One of these adjustments are the interrupt mitigation techniques implemented by modern network interface cards and operating systems. Using these, an administrator can optimize either lower latencies or lower CPU overhead for processing of network traffic. In this work, an analytical model that allows computing relevant performance metrics like the packet processing time and the packet loss for generic virtualized network functions running on commodity hardware is developed. The applicability of the model is shown by comparing its outcome with measurements conducted in a local testbed. Based on this model, impact factors like the average packet interarrival time, the interarrival time distribution, and the duration of the interrupt aggregation interval are studied.
  @inproceedings{info3-inproceedings-2016-4, abstract = {The softwarization of networks promises cost savings and better scalability of network functions by moving functionality from specialized devices into commercial off-the-shelf hardware. Generalized computing hardware offers many degrees for adjustment and tuning, which can affect performance and resource utilization. One of these adjustments are the interrupt mitigation techniques implemented by modern network interface cards and operating systems. Using these, an administrator can optimize either lower latencies or lower CPU overhead for processing of network traffic. In this work, an analytical model that allows computing relevant performance metrics like the packet processing time and the packet loss for generic virtualized network functions running on commodity hardware is developed. The applicability of the model is shown by comparing its outcome with measurements conducted in a local testbed. Based on this model, impact factors like the average packet interarrival time, the interarrival time distribution, and the duration of the interrupt aggregation interval are studied.}, address = {Würzburg, Germany}, author = {Gebert, Steffen and Zinner, Thomas and Lange, Stanislav and Schwartz, Christian and Tran-Gia, Phuoc}, booktitle = {28th International Teletraffic Congress (ITC)}, month = 9, title = {Performance Modeling of Softwarized Network Functions Using Discrete-Time Analysis}, year = 2016 }
• Höfner, S.: Evaluation of Orchestration and Access Principles for Cloud Applications, (2016).
  [ Abstract ] [ BibTeX ]
   
  The main goal of this thesis is to define, analyze, and evaluate different orchestration and access principles of highly distributed Internet applications. For this purpose, different cloud application types have to be defined. Thereafter three different ap- plications are modeled, measured, and evaluated during the course of this thesis, namely a cloud based picture gallery, a distributed video streaming application and an interactive image processing application. These applications are supposed to run within an existing OpenStack environment that was developed during an earlier Master’s thesis. In the modeling process of the applications, it has to be taken into account that these applications should be scalable in the horizontal, as well as in the vertical dimension. Scaling in the horizontal dimension corresponds to the duplication or migration of services to different locations on the Internet, while the vertical scaling of an application refers to the scaling of the application scope, the complexity of the application functionality, or the provided content quality for specific users. The remainder of this work is structured as follows: Background information about cloud applications and their architecture is presented in Chapter 2. Thereafter, we discuss work that is related to this thesis in Chapter 3. This is followed by a characterization of different cloud application types in Chapter 4. After that, the orchestration and access principles that are important to this work are briefly de- scribed in Chapter 5. Subsequently, we introduce the cloud applications and their corresponding testbeds that have been developed during this thesis in Chapter 6. These applications are then evaluated under consideration of the previously de- scribed orchestration and access principles in Chapter 7. Finally, we conclude this thesis and try to give an outlook for further work in this area in Chapter 8.
  @mastersthesis{info3-master-2016-7, abstract = {The main goal of this thesis is to define, analyze, and evaluate different orchestration and access principles of highly distributed Internet applications. For this purpose, different cloud application types have to be defined. Thereafter three different ap- plications are modeled, measured, and evaluated during the course of this thesis, namely a cloud based picture gallery, a distributed video streaming application and an interactive image processing application. These applications are supposed to run within an existing OpenStack environment that was developed during an earlier Master’s thesis. In the modeling process of the applications, it has to be taken into account that these applications should be scalable in the horizontal, as well as in the vertical dimension. Scaling in the horizontal dimension corresponds to the duplication or migration of services to different locations on the Internet, while the vertical scaling of an application refers to the scaling of the application scope, the complexity of the application functionality, or the provided content quality for specific users. The remainder of this work is structured as follows: Background information about cloud applications and their architecture is presented in Chapter 2. Thereafter, we discuss work that is related to this thesis in Chapter 3. This is followed by a characterization of different cloud application types in Chapter 4. After that, the orchestration and access principles that are important to this work are briefly de- scribed in Chapter 5. Subsequently, we introduce the cloud applications and their corresponding testbeds that have been developed during this thesis in Chapter 6. These applications are then evaluated under consideration of the previously de- scribed orchestration and access principles in Chapter 7. Finally, we conclude this thesis and try to give an outlook for further work in this area in Chapter 8.}, author = {Höfner, Steffen}, month = 9, school = {University of Würzburg}, title = {Evaluation of Orchestration and Access Principles for Cloud Applications}, year = 2016 }
• Münster, S., Kröber, C., Friedrichs, K., Bruschke, J., Henze, F., Niebling, F.: Neue Wege stadtgeschichtlicher Forschung und Vermittlung. In: Bienert, A., Börner, A., Emenlauer-Blömers, E., und Hemsley, J. (hrsg.) Elektronische Medien & Kunst, Kultur und Historie (EVA). S. 214-221 (2016).
  [ BibTeX ]
   
  @inproceedings{munster2016eva, author = {Münster, Sander and Kröber, Cindy and Friedrichs, Kristina and Bruschke, Jonas and Henze, Frank and Niebling, Florian}, booktitle = {Elektronische Medien & Kunst, Kultur und Historie (EVA)}, editor = {Bienert, Andreas and Börner, Anko and Emenlauer-Blömers, Eva and Hemsley, James}, pages = {214-221}, title = {Neue Wege stadtgeschichtlicher Forschung und Vermittlung}, year = 2016 }
• Chaplick, S., Fleszar, K., Lipp, F., Ravsky, A., Verbitsky, O., Wolff, A.: Drawing Graphs on Few Lines and Few Planes. In: Hu, Y. und Nöllenburg, M. (hrsg.) Proc. 24th Int. Sympos. Graph Drawing Network Vis. (GD'16). S. 166-180. Springer (2016).
  [ BibTeX ] [ URL ]
   
  @inproceedings{cflrvw-dgoflafp-GD16, author = {Chaplick, Steven and Fleszar, Krzysztof and Lipp, Fabian and Ravsky, Alexander and Verbitsky, Oleg and Wolff, Alexander}, booktitle = {Proc. 24th Int. Sympos. Graph Drawing Network Vis. (GD'16)}, editor = {Hu, Yifan and Nöllenburg, Martin}, pages = {166-180}, publisher = {Springer}, title = {Drawing Graphs on Few Lines and Few Planes}, volume = 9801, year = 2016 }
• van Dijk, T.C., Fink, M., Fischer, N., Lipp, F., Markfelder, P., Ravsky, A., Suri, S., Wolff, A.: Block Crossings in Storyline Visualizations. In: Hu, Y. und Nöllenburg, M. (hrsg.) Proc. 24th Int. Sympos. Graph Drawing Network Vis. (GD'16). S. 382-398. Springer-Verlag (2016).
  [ BibTeX ] [ URL ]
   
  @inproceedings{DBLP:journals/corr/Dijk0FLMRSW16, author = {van Dijk, Thomas C. and Fink, Martin and Fischer, Norbert and Lipp, Fabian and Markfelder, Peter and Ravsky, Alexander and Suri, Subhash and Wolff, Alexander}, booktitle = {Proc. 24th Int. Sympos. Graph Drawing Network Vis. (GD'16)}, editor = {Hu, Yifan and Nöllenburg, Martin}, note = {Best paper award.}, pages = {382-398}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Block Crossings in Storyline Visualizations}, volume = 9801, year = 2016 }
• Haunert, J.-H., Wolff, A.: Räumliche Analyse durch kombinatorische Optimierung. In: Freeden, W. und Rummel, R. (hrsg.) Handbuch der Geodäsie (6 Bände). S. 1--39. Springer Berlin Heidelberg (2016).
  [ BibTeX ] [ URL ] [ DOI ]
   
  @incollection{hw-rako-HG16, author = {Haunert, Jan-Henrik and Wolff, Alexander}, booktitle = {Handbuch der Geodäsie (6 Bände)}, editor = {Freeden, Willi and Rummel, Reiner}, pages = {1--39}, publisher = {Springer Berlin Heidelberg}, title = {Räumliche Analyse durch kombinatorische Optimierung}, year = 2016 }
• Budig, B., Dijk, T.C.V., Wolff, A.: Matching Labels and Markers in Historical Maps: An Algorithm with Interactive Postprocessing. ACM Trans. Spatial Algorithms Syst. 2, 13:1--13:24 (2016).
  [ BibTeX ] [ URL ] [ DOI ]
   
  @article{bdw-mlmh-TSAS16, author = {Budig, Benedikt and Dijk, Thomas C. Van and Wolff, Alexander}, journal = {ACM Trans. Spatial Algorithms Syst.}, number = 4, pages = {13:1--13:24}, title = {Matching Labels and Markers in Historical Maps: An Algorithm with Interactive Postprocessing}, volume = 2, year = 2016 }
• Pfaff, B.: A Behavior-driven Approach for Testing Softwarized Networks using OpenStack Infrastructures, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-praktikum-2016-3, author = {Pfaff, Benedikt}, month = 8, school = {Universität Würzburg}, title = {A Behavior-driven Approach for Testing Softwarized Networks using OpenStack Infrastructures}, year = 2016 }
• Reinhart, L.: An SDN-based Implementation of a Network-controlled “Bring Your Own Device” Scenario, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-praktikum-2016-4, author = {Reinhart, Lorenz}, month = 8, school = {Universität Würzburg}, title = {An SDN-based Implementation of a Network-controlled “Bring Your Own Device” Scenario}, year = 2016 }
• Werthmann, A.: Untersuchung der Sicherheit von Desktop- und Smartphone-Applikationen hinsichtlich HTTPS-Man-in-the-middle-Angrifen, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-praktikum-2016-5, author = {Werthmann, Alexander}, month = 8, school = {Universität Würzburg}, title = {Untersuchung der Sicherheit von Desktop- und Smartphone-Applikationen hinsichtlich HTTPS-Man-in-the-middle-Angrifen}, year = 2016 }
• Chaplick, S., Lipp, F., Park, J.-won, Wolff, A.: Obstructing Visibilities with One Obstacle. In: Hu, Y. und Nöllenburg, M. (hrsg.) Proc. 24th Int. Symp. Graph Drawing & Network Vis. (GD'16). S. 295--308. Springer-Verlag (2016).
  [ BibTeX ] [ URL ] [ DOI ]
   
  @inproceedings{clpw-ov1o-GD16, author = {Chaplick, Steven and Lipp, Fabian and Park, Ji-won and Wolff, Alexander}, booktitle = {Proc. 24th Int. Symp. Graph Drawing & Network Vis. (GD'16)}, editor = {Hu, Yifan and Nöllenburg, Martin}, pages = {295--308}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Obstructing Visibilities with One Obstacle}, volume = 9801, year = 2016 }
• Seufert, M.: Automated Decision Making Methods for the Multi-objective Optimization Task of Cloud Service Placement. , 1st International Workshop on Programmability for Cloud Networks and Applications (PROCON), Würzburg, Germany (2016).
  [ BibTeX ]
   
  @presentation{info3-presentation-2016-9, address = {1st International Workshop on Programmability for Cloud Networks and Applications (PROCON), Würzburg, Germany}, author = {Seufert, Michael}, month = 9, title = {Automated Decision Making Methods for the Multi-objective Optimization Task of Cloud Service Placement}, year = 2016 }
• Chaplick, S., Lipp, F., Park, J.-W., Wolff, A.: Obstructing Visibilities with One Obstacle. In: Hu, Y. und Nöllenburg, M. (hrsg.) Proceedings of the 24th Int. Symp. on Graph Drawing & Network Visualization. S. 295-308. Springer (2016).
  [ BibTeX ] [ URL ]
   
  @inproceedings{clpw-obwoo-GD16, author = {Chaplick, Steven and Lipp, Fabian and Park, Ji-Won and Wolff, Alexander}, booktitle = {Proceedings of the 24th Int. Symp. on Graph Drawing & Network Visualization}, editor = {Hu, Yifan and Nöllenburg, Martin}, pages = {295-308}, publisher = {Springer}, title = {Obstructing Visibilities with One Obstacle}, volume = 9801, year = 2016 }
• Sasu, B.: Investigation of Analytical Modeling Approaches for Edge Computing, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2016-9, author = {Sasu, Bianca}, month = 9, school = {University of Würzburg}, title = {Investigation of Analytical Modeling Approaches for Edge Computing}, year = 2016 }
• Zimmerer, C., Fischbach, M., Latoschik, M.E.: Maintainable Management and Access of Lexical Knowledge for Multimodal Virtual Reality Interfaces. Proceeding of the 22nd ACM Symposium on Virtual Reality Software and Technology (VRST). ACM (2016).
  [ Abstract ] [ BibTeX ]
   
  This poster presents a maintainable method to manage lexical information required for multimodal interfaces. It is tailored for the application in real-time interactive systems, specifically for Virtual Reality, and solves three problems commonly encountered in this context: (1) The lexical information is defined on and grounded in a common knowledge representation layer (KRL) based on OWL. The KRL describes application objects and possible system functions in one place and avoids error-prone redundant data management. (2) The KRL is tightly integrated into the simulator platform using a semantically enriched object model that is auto-generated from the KRL and thus fosters high performance access. (3) A well-defined interface provides application wide access to semantic application state information in general and the lexical information in specific, which greatly contributes to decoupling, maintainability, and reusability.
  @inproceedings{zimmerer2016maintainable, abstract = {This poster presents a maintainable method to manage lexical information required for multimodal interfaces. It is tailored for the application in real-time interactive systems, specifically for Virtual Reality, and solves three problems commonly encountered in this context: (1) The lexical information is defined on and grounded in a common knowledge representation layer (KRL) based on OWL. The KRL describes application objects and possible system functions in one place and avoids error-prone redundant data management. (2) The KRL is tightly integrated into the simulator platform using a semantically enriched object model that is auto-generated from the KRL and thus fosters high performance access. (3) A well-defined interface provides application wide access to semantic application state information in general and the lexical information in specific, which greatly contributes to decoupling, maintainability, and reusability.}, author = {Zimmerer, Chris and Fischbach, Martin and Latoschik, Marc Erich}, booktitle = {Proceeding of the 22nd ACM Symposium on Virtual Reality Software and Technology (VRST)}, publisher = {ACM}, title = {Maintainable Management and Access of Lexical Knowledge for Multimodal Virtual Reality Interfaces}, year = 2016 }
• Zeidler, B.: Comparison of Machine Learning Approaches for YouTube Video Adaptation Estimation on Encrypted Traffic, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2016-8, author = {Zeidler, Bernd}, month = 9, school = {University of Würzburg}, title = {Comparison of Machine Learning Approaches for YouTube Video Adaptation Estimation on Encrypted Traffic}, year = 2016 }
• Latoschik, M.E., Lugrin, J.-L., Roth, D.: FakeMi: A Fake Mirror System for Avatar Embodiment Studies. Proceeding of the 22nd ACM Symposium on Virtual Reality Software and Technology (VRST) (2016).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  This paper introduces a fake mirror system as a research tool to study the effect of avatar embodiment with a non-immersive virtual environment. The system combines marker-less face and body tracking to animate the individual avatars seen in a stereoscopic display with a correct perspective projection. The display dimensions match typical dimensions of a real physical mirror and the animated avatars are rendered based on a geometrically correct reflection as expected from a real mirror including correct body and face animations. The first evaluation of the system reveals the high acceptance of the setup as well as a convincing illusion of a real mirror with different types of avatars.
  @inproceedings{latoschik2016fakemi, abstract = {This paper introduces a fake mirror system as a research tool to study the effect of avatar embodiment with a non-immersive virtual environment. The system combines marker-less face and body tracking to animate the individual avatars seen in a stereoscopic display with a correct perspective projection. The display dimensions match typical dimensions of a real physical mirror and the animated avatars are rendered based on a geometrically correct reflection as expected from a real mirror including correct body and face animations. The first evaluation of the system reveals the high acceptance of the setup as well as a convincing illusion of a real mirror with different types of avatars.}, author = {Latoschik, Marc Erich and Lugrin, Jean-Luc and Roth, Daniel}, booktitle = {Proceeding of the 22nd ACM Symposium on Virtual Reality Software and Technology (VRST)}, title = {FakeMi: A Fake Mirror System for Avatar Embodiment Studies}, year = 2016 }
• Gray, N., Zinner, T., Gebert, S., Tran-Gia, P.: Simulation Framework for Distributed SDN-Controller Architectures in OMNeT++. 8th EAI International Conference on Mobile Networks and Management (MONAMI 2016). , Abu Dhabi, United Arab Emirates (2016).
  [ Abstract ] [ BibTeX ]
   
  SDN introduces the seperation of network control and network data plane. The control plane is removed from distributed network entities and logically centralized as the SDN controller. To provide resilience and performance such a logically centralized controller may again be physically distributed. Scenarios featuring distributed controller architectures include data center deployments, where controller instances synchronize states on small distances and delays, or continental WAN deployments with long distances and delays between controllers. The contribution of this paper is an OMNET++ based simulation framework for assessing the performance of distributed SDN controller architectures. Relevant protocols and controller applications are modelled with a high level of detail. Further, an exemplary implementation of two different controller architectures, namely Hyperflow and Kandoo, is included. Initial results based on the provided implementations are presented.
  @inproceedings{info3-inproceedings-2016-20, abstract = {SDN introduces the seperation of network control and network data plane. The control plane is removed from distributed network entities and logically centralized as the SDN controller. To provide resilience and performance such a logically centralized controller may again be physically distributed. Scenarios featuring distributed controller architectures include data center deployments, where controller instances synchronize states on small distances and delays, or continental WAN deployments with long distances and delays between controllers. The contribution of this paper is an OMNET++ based simulation framework for assessing the performance of distributed SDN controller architectures. Relevant protocols and controller applications are modelled with a high level of detail. Further, an exemplary implementation of two different controller architectures, namely Hyperflow and Kandoo, is included. Initial results based on the provided implementations are presented.}, address = {Abu Dhabi, United Arab Emirates}, author = {Gray, Nicholas and Zinner, Thomas and Gebert, Steffen and Tran-Gia, Phuoc}, booktitle = {8th EAI International Conference on Mobile Networks and Management (MONAMI 2016)}, month = 10, title = {Simulation Framework for Distributed SDN-Controller Architectures in OMNeT++}, year = 2016 }
• Seufert, M.: Test Effects in Crowdtesting. , Qualinet Crowdsourcing TF Meeting, Berlin, Germany (2016).
  [ BibTeX ]
   
  @presentation{info3-presentation-2016-8, address = {Qualinet Crowdsourcing TF Meeting, Berlin, Germany}, author = {Seufert, Michael}, month = 9, title = {Test Effects in Crowdtesting}, year = 2016 }
• Becker, M., Mewes, H., Hotho, A., Dimitrov, D., Lemmerich, F., Strohmaier, M.: SparkTrails: A MapReduce Implementation of HypTrails for Comparing Hypotheses About Human Trails. In: Bourdeau, J., Hendler, J., Nkambou, R., Horrocks, I., und Zhao, B.Y. (hrsg.) WWW (Companion Volume). S. 17-18. ACM (2016).
  [ BibTeX ] [ URL ]
   
  @inproceedings{conf/www/0003MHDLS16, author = {Becker, Martin and Mewes, Hauke and Hotho, Andreas and Dimitrov, Dimitar and Lemmerich, Florian and Strohmaier, Markus}, booktitle = {WWW (Companion Volume)}, crossref = {conf/www/2016c}, editor = {Bourdeau, Jacqueline and Hendler, Jim and Nkambou, Roger and Horrocks, Ian and Zhao, Ben Y.}, pages = {17-18}, publisher = {ACM}, title = {SparkTrails: A MapReduce Implementation of HypTrails for Comparing Hypotheses About Human Trails.}, year = 2016 }
• Zorn, F.: Methods for Improving the Qualitiy of Experience of Mobile Video Streams, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-bachelor-2016-10, author = {Zorn, Florian}, month = 11, school = {University of Würzburg}, title = {Methods for Improving the Qualitiy of Experience of Mobile Video Streams}, year = 2016 }
• Cellier, P., Charnois, T., Hotho, A., Matwin, S., Moens, M.-F., Toussaint, Y. hrsg: Proceedings of the Workshop on Interactions between Data Mining and Natural Language Processing, DMNLP 2016, co-located with the European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases, ECML-PKDD 2016, Riva del Garda, Italy, September 23, 2016. CEUR-WS.org (2016).
  [ BibTeX ] [ URL ]
   
  @proceedings{conf/pkdd/2016dmnlp, booktitle = {DMNLP@PKDD/ECML}, editor = {Cellier, Peggy and Charnois, Thierry and Hotho, Andreas and Matwin, Stan and Moens, Marie-Francine and Toussaint, Yannick}, publisher = {CEUR-WS.org}, series = {CEUR Workshop Proceedings}, title = {Proceedings of the Workshop on Interactions between Data Mining and Natural Language Processing, DMNLP 2016, co-located with the European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases, ECML-PKDD 2016, Riva del Garda, Italy, September 23, 2016.}, volume = 1646, year = 2016 }
• Niebler, T., Schlör, D., Becker, M., Hotho, A.: Extracting Semantics from Unconstrained Navigation on Wikipedia. KI. 30, 163-168 (2016).
  [ BibTeX ] [ URL ]
   
  @article{journals/ki/NieblerS0H16, author = {Niebler, Thomas and Schlör, Daniel and Becker, Martin and Hotho, Andreas}, journal = {KI}, number = 2, pages = {163-168}, title = {Extracting Semantics from Unconstrained Navigation on Wikipedia}, volume = 30, year = 2016 }
• Zehe, A., Becker, M., Hettinger, L., Hotho, A., Reger, I., Jannidis, F.: Prediction of Happy Endings in German Novels. In: Cellier, P., Charnois, T., Hotho, A., Matwin, S., Moens, M.-F., und Toussaint, Y. (hrsg.) DMNLP@PKDD/ECML. S. 9-16. CEUR-WS.org (2016).
  [ BibTeX ] [ URL ]
   
  @inproceedings{zehe2016prediction, author = {Zehe, Albin and Becker, Martin and Hettinger, Lena and Hotho, Andreas and Reger, Isabella and Jannidis, Fotis}, booktitle = {DMNLP@PKDD/ECML}, crossref = {conf/pkdd/2016dmnlp}, editor = {Cellier, Peggy and Charnois, Thierry and Hotho, Andreas and Matwin, Stan and Moens, Marie-Francine and Toussaint, Yannick}, pages = {9-16}, publisher = {CEUR-WS.org}, series = {CEUR Workshop Proceedings}, title = {Prediction of Happy Endings in German Novels}, volume = 1646, year = 2016 }
• Lemmerich, F., Becker, M., Singer, P., Helic, D., Hotho, A., Strohmaier, M.: Mining Subgroups with Exceptional Transition Behavior. In: Krishnapuram, B., Shah, M., Smola, A.J., Aggarwal, C., Shen, D., und Rastogi, R. (hrsg.) KDD. S. 965-974. ACM (2016).
  [ BibTeX ] [ URL ]
   
  @inproceedings{lemmerich2016mining, author = {Lemmerich, Florian and Becker, Martin and Singer, Philipp and Helic, Denis and Hotho, Andreas and Strohmaier, Markus}, booktitle = {KDD}, crossref = {conf/kdd/2016}, editor = {Krishnapuram, Balaji and Shah, Mohak and Smola, Alexander J. and Aggarwal, Charu and Shen, Dou and Rastogi, Rajeev}, pages = {965-974}, publisher = {ACM}, title = {Mining Subgroups with Exceptional Transition Behavior}, year = 2016 }
• Budig, B.: Efficient Algorithms and User Interaction for Metadata Extraction from Historical Maps. Proceedings of the 2nd ACM SIGSPATIAL PhD Workshop. S. 4:1--4:4. ACM, Bellevue, Washington (2016).
  [ Abstract ] [ BibTeX ] [ URL ] [ DOI ]
   
  In this research project we develop a system for metadata extraction from historical maps. Such maps are valuable sources of information for researchers of various disciplines. However, metadata describing their (geographic) contents are scarce, because such information mostly has to be extracted by hand. Examining related work, we find that no holistic, automated solutions for this problem have been developed so far. Our system aims at speeding up the process of metadata extraction, using efficient algorithms combined with user interaction. We present our approach, which is a pipeline consisting of several steps. The layout of this system is modular; we discuss two modules in the pipeline that we have already developed and sketch our solutions. We conclude this report with an outlook and future work, which includes crowdsourcing applications.
  @inproceedings{Budig:2015:EAU:2855680.2855841, abstract = {In this research project we develop a system for metadata extraction from historical maps. Such maps are valuable sources of information for researchers of various disciplines. However, metadata describing their (geographic) contents are scarce, because such information mostly has to be extracted by hand. Examining related work, we find that no holistic, automated solutions for this problem have been developed so far. Our system aims at speeding up the process of metadata extraction, using efficient algorithms combined with user interaction. We present our approach, which is a pipeline consisting of several steps. The layout of this system is modular; we discuss two modules in the pipeline that we have already developed and sketch our solutions. We conclude this report with an outlook and future work, which includes crowdsourcing applications.}, address = {New York, NY, USA}, author = {Budig, Benedikt}, booktitle = {Proceedings of the 2nd ACM SIGSPATIAL PhD Workshop}, pages = {4:1--4:4}, publisher = {ACM}, series = {SIGSPATIAL PhD '15}, title = {Efficient Algorithms and User Interaction for Metadata Extraction from Historical Maps}, year = 2016 }
• Ly, N.T., Preßler, J., Gall, D., Hurtienne, J., Huber, S.: Tangible interaction drawers for people with dementia: retrieving living experiences from past memories. Proceedings of the 2016 ACM International Joint Conference on Pervasive and Ubiquitous Computing (UbiComp): Adjunct. S. 157-160. ACM (2016).
  [ BibTeX ]
   
  @inproceedings{noauthororeditor2016tangible, author = {Ly, Nam Tung and Preßler, Jan and Gall, Dominik and Hurtienne, Jörn and Huber, Stephan}, booktitle = {Proceedings of the 2016 ACM International Joint Conference on Pervasive and Ubiquitous Computing (UbiComp): Adjunct}, organization = {ACM}, pages = {157-160}, title = {Tangible interaction drawers for people with dementia: retrieving living experiences from past memories}, year = 2016 }
• Gebert, S., Müssig, A., Lange, S., Zinner, T., Gray, N., Tran-Gia, P.: Processing Time Comparison of a Hardware-Based Firewall and its Virtualized Counterpart. 8th EAI International Conference on Mobile Networks and Management (MONAMI 2016). , Abu Dhabi, United Arab Emirates (2016).
  [ BibTeX ]
   
  @inproceedings{info3-inproceedings-2016-19, address = {Abu Dhabi, United Arab Emirates}, author = {Gebert, Steffen and Müssig, Alexander and Lange, Stanislav and Zinner, Thomas and Gray, Nicholas and Tran-Gia, Phuoc}, booktitle = {8th EAI International Conference on Mobile Networks and Management (MONAMI 2016)}, month = 10, title = {Processing Time Comparison of a Hardware-Based Firewall and its Virtualized Counterpart}, year = 2016 }
• Stauffert, J.-P., Niebling, F., Latoschik, M.E.: Towards Comparable Evaluation Methods and Measures for Timing Behaviour of Virtual Reality Systems. Proceeding of the 22nd ACM Symposium on Virtual Reality Software and Technology (VRST) (2016).
  [ BibTeX ] [ URL ]
   
  @inproceedings{stauffert2016towards, author = {Stauffert, Jan-Philipp and Niebling, Florian and Latoschik, Marc Erich}, booktitle = {Proceeding of the 22nd ACM Symposium on Virtual Reality Software and Technology (VRST)}, title = {Towards Comparable Evaluation Methods and Measures for Timing Behaviour of Virtual Reality Systems}, year = 2016 }
• Oberdörfer, S., Latoschik, M.E.: Interactive Gamified 3D-Training of Affine Transformations. Proceeding of the 22nd ACM Symposium on Virtual Reality Software and Technology (VRST) (2016).
  [ BibTeX ]
   
  @inproceedings{oberdorfer2016interactive, author = {Oberdörfer, Sebastian and Latoschik, Marc Erich}, booktitle = {Proceeding of the 22nd ACM Symposium on Virtual Reality Software and Technology (VRST)}, title = {Interactive Gamified 3D-Training of Affine Transformations}, year = 2016 }
• Burger, V., Hirth, M., Hoßfeld, T., Tran-Gia, P.: Principles of Information Neutrality and Counter Measures Against Biased Information. Lecture Notes in Informatics: Value-Sensitive Design of Internet-Based Services. , Klagenfurt, Austria (2016).
  [ Abstract ] [ BibTeX ]
   
  The Internet serves as ubiquitous, prompt source of information in our society. Due to the giant amount of information, the access to the information relies on information processing mechanisms as implemented in search engines, product recommendation systems, or online social networks. As a result of the engineered preprocessing mechanism, the retrieved information is biased and does not represent a neutral view on the available information, while end-users often are not aware of this bias. In this article, we define the term “Information Neutrality”, review current principles of information processing in the Internet and discuss influence factors hindering Information Neutrality as well as appropriate countermeasures. The main contribution of this article is to raise the awareness of Information Neutrality as an emerging key challenge in the Internet and to potentially consider Information Neutrality as a factor in the value-sensitive design of Internet-based services.
  @inproceedings{info3-inproceedings-2016-21, abstract = {The Internet serves as ubiquitous, prompt source of information in our society. Due to the giant amount of information, the access to the information relies on information processing mechanisms as implemented in search engines, product recommendation systems, or online social networks. As a result of the engineered preprocessing mechanism, the retrieved information is biased and does not represent a neutral view on the available information, while end-users often are not aware of this bias. In this article, we define the term “Information Neutrality”, review current principles of information processing in the Internet and discuss influence factors hindering Information Neutrality as well as appropriate countermeasures. The main contribution of this article is to raise the awareness of Information Neutrality as an emerging key challenge in the Internet and to potentially consider Information Neutrality as a factor in the value-sensitive design of Internet-based services.}, address = {Klagenfurt, Austria}, author = {Burger, Valentin and Hirth, Matthias and Hoßfeld, Tobias and Tran-Gia, Phuoc}, booktitle = {Lecture Notes in Informatics: Value-Sensitive Design of Internet-Based Services}, month = 9, title = {Principles of Information Neutrality and Counter Measures Against Biased Information}, year = 2016 }
• König, F.: Cloud Computing with OpenStack: Deployment and Networking, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-praktikum-2016-7, author = {König, Frederik}, month = 9, school = {University of Würzburg}, title = {Cloud Computing with OpenStack: Deployment and Networking}, year = 2016 }
• Schreck, M.: Matlab REST API, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-praktikum-2016-8, author = {Schreck, Marco}, month = 3, school = {University of Würzburg}, title = {Matlab REST API}, year = 2016 }
• Schmitt, N.: Implementation of a Video Quality Reference Metric for H264 using ffmpeg, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-praktikum-2016-6, author = {Schmitt, Norbert}, month = 9, school = {Universität Würzburg}, title = {Implementation of a Video Quality Reference Metric for H264 using ffmpeg}, year = 2016 }
• Helmschrott, F.: Measurement-based Performance Assessment of the QUIC Web Transport Protocol, (2016).
  [ BibTeX ]
   
  @mastersthesis{info3-master-2016-11, author = {Helmschrott, Fabian}, month = 12, school = {University of Würzburg}, title = {Measurement-based Performance Assessment of the QUIC Web Transport Protocol}, year = 2016 }
• Kröber, C., Münster, S., Friedrichs, K., Niebling, F.: Researching historic photos – Visualizations and potentials beyond the image. Gehalten auf der (2016).
  [ BibTeX ]
   
  @inproceedings{krober2016researching, author = {Kröber, Cindy and Münster, Sander and Friedrichs, Kristina and Niebling, Florian}, title = {Researching historic photos – Visualizations and potentials beyond the image}, year = 2016 }
• Seufert, M., Casas, P., Wamser, F., Wehner, N., Schatz, R., Tran-Gia, P.: Application-Layer Monitoring of QoE Parameters for Mobile YouTube Video Streaming in the Field. IEEE 6th International Conference on Communications and Electronics (ICCE). , Ha Long, Vietnam (2016).
  [ Abstract ] [ BibTeX ]
   
  YouTube video streaming is one of the most popular and most demanding services in cellular networks. Thus, operators are concerned about the quality of the streaming delivered by their networks and would like to monitor the Quality of Experience (QoE) of the end users. In this work, we conduct a field study of mobile YouTube video streaming, in which both network flow parameters and application-layer streaming parameters were monitored, and present the characteristics of current mobile YouTube streaming. The impact of both approaches is investigated showing that monitoring network parameters is not sufficient to directly infer the resulting QoE. In contrast, the streaming parameters, which can be obtained from application-layer monitoring, show high correlations to the subjectively experienced quality, and thus, are better suited for QoE monitoring.
  @inproceedings{info3-inproceedings-2016-9, abstract = {YouTube video streaming is one of the most popular and most demanding services in cellular networks. Thus, operators are concerned about the quality of the streaming delivered by their networks and would like to monitor the Quality of Experience (QoE) of the end users. In this work, we conduct a field study of mobile YouTube video streaming, in which both network flow parameters and application-layer streaming parameters were monitored, and present the characteristics of current mobile YouTube streaming. The impact of both approaches is investigated showing that monitoring network parameters is not sufficient to directly infer the resulting QoE. In contrast, the streaming parameters, which can be obtained from application-layer monitoring, show high correlations to the subjectively experienced quality, and thus, are better suited for QoE monitoring.}, address = {Ha Long, Vietnam}, author = {Seufert, Michael and Casas, Pedro and Wamser, Florian and Wehner, Nikolas and Schatz, Raimund and Tran-Gia, Phuoc}, booktitle = {IEEE 6th International Conference on Communications and Electronics (ICCE)}, month = 7, title = {Application-Layer Monitoring of QoE Parameters for Mobile YouTube Video Streaming in the Field}, year = 2016 }
• Aschenbrenner, D., Latoschik, M.E., Schilling, K.: Industrial Maintenance with Augmented Reality: Two Case Studies. Proceedings of the 22nd ACM Symposium on Virtual Reality Software and Technology (VRST). ACM (2016).
  [ BibTeX ]
   
  @inproceedings{aschenbrenner2016industrial, author = {Aschenbrenner, Doris and Latoschik, Marc Erich and Schilling, Klaus}, booktitle = {Proceedings of the 22nd ACM Symposium on Virtual Reality Software and Technology (VRST)}, publisher = {ACM}, title = {Industrial Maintenance with Augmented Reality: Two Case Studies}, year = 2016 }
• Seufert, M.: One Shot Crowdtesting: Approaching the Extremes of Crowdsourced Subjective Quality Testing. , 5th ISCA/DEGA Workshop on Perceptual Quality of Systems (PQS), Berlin, Germany (2016).
  [ BibTeX ]
   
  @presentation{info3-presentation-2016-7, address = {5th ISCA/DEGA Workshop on Perceptual Quality of Systems (PQS), Berlin, Germany}, author = {Seufert, Michael}, month = 8, title = {One Shot Crowdtesting: Approaching the Extremes of Crowdsourced Subjective Quality Testing}, year = 2016 }
• Hettinger, L., Jannidis, F., Reger, I., Hotho, A.: Significance Testing for the Classification of Literary Subgenres. DH 2016 (2016).
  [ BibTeX ]
   
  @inproceedings{hettinger2016significance, author = {Hettinger, Lena and Jannidis, Fotis and Reger, Isabella and Hotho, Andreas}, booktitle = {DH 2016}, title = {Significance Testing for the Classification of Literary Subgenres}, year = 2016 }
• Seufert, M., Burger, V., Kaup, F.: Evaluating the Impact of WiFi Offloading on Mobile Users of HTTP Adaptive Video Streaming. 5th IEEE International Workshop on Quality of Experience for Multimedia Communications (QoEMC). , Washington, DC, USA (2016).
  [ Abstract ] [ BibTeX ]
   
  In a recent trend to lessen the load on cellular networks in cities, users are offered to offload mobile connections to lower cost WiFi networks. In this work, we conduct a simulative performance evaluation of the impact of WiFi offloading for a mobile end user of a HTTP adaptive video streaming (HAS) service depending on availability and range of the WiFi hotspots. The simulation is based on connectivity measurements from a German city and evaluates the key performance indicators for the QoE of HAS, i.e., initial delay, stalling, and quality adaptation. Additionally, a smartphone energy model is applied to assess the energy consumption during the streaming. The results indicate that WiFi offloading of HAS connections to public WiFi hotspots is not attractive for end users both in terms of QoE and energy consumption. However, it can be shown that WiFi offloading can be beneficial also for end users in case high bandwidths can be received via WiFi.
  @inproceedings{info3-inproceedings-2016-18, abstract = {In a recent trend to lessen the load on cellular networks in cities, users are offered to offload mobile connections to lower cost WiFi networks. In this work, we conduct a simulative performance evaluation of the impact of WiFi offloading for a mobile end user of a HTTP adaptive video streaming (HAS) service depending on availability and range of the WiFi hotspots. The simulation is based on connectivity measurements from a German city and evaluates the key performance indicators for the QoE of HAS, i.e., initial delay, stalling, and quality adaptation. Additionally, a smartphone energy model is applied to assess the energy consumption during the streaming. The results indicate that WiFi offloading of HAS connections to public WiFi hotspots is not attractive for end users both in terms of QoE and energy consumption. However, it can be shown that WiFi offloading can be beneficial also for end users in case high bandwidths can be received via WiFi.}, address = {Washington, DC, USA}, author = {Seufert, Michael and Burger, Valentin and Kaup, Fabian}, booktitle = {5th IEEE International Workshop on Quality of Experience for Multimedia Communications (QoEMC)}, month = 12, title = {Evaluating the Impact of WiFi Offloading on Mobile Users of HTTP Adaptive Video Streaming}, year = 2016 }
• Niebler, T., Becker, M., Zoller, D., Doerfel, S., Hotho, A.: FolkTrails: Interpreting Navigation Behavior in a Social Tagging System. Proceedings of the 25th ACM International on Conference on Information and Knowledge Management. ACM, New York, NY, USA (2016).
  [ Abstract ] [ BibTeX ] [ URL ]
   
  Social tagging systems have established themselves as a quick and easy way to organize information by annotating resources with tags. In recent work, user behavior in social tagging systems was studied, that is, how users assign tags, and consume content. However, it is still unclear how users make use of the navigation options they are given. Understanding their behavior and differences in behavior of different user groups is an important step towards assessing the effectiveness of a navigational concept and of improving it to better suit the users’ needs. In this work, we investigate navigation trails in the popular scholarly social tagging system BibSonomy from six years of log data. We discuss dynamic browsing behavior of the general user population and show that different navigational subgroups exhibit different navigational traits. Furthermore, we provide strong evidence that the semantic nature of the underlying folksonomy is an essential factor for explaining navigation.
  @inproceedings{niebler2016folktrails, abstract = {Social tagging systems have established themselves as a quick and easy way to organize information by annotating resources with tags. In recent work, user behavior in social tagging systems was studied, that is, how users assign tags, and consume content. However, it is still unclear how users make use of the navigation options they are given. Understanding their behavior and differences in behavior of different user groups is an important step towards assessing the effectiveness of a navigational concept and of improving it to better suit the users’ needs. In this work, we investigate navigation trails in the popular scholarly social tagging system BibSonomy from six years of log data. We discuss dynamic browsing behavior of the general user population and show that different navigational subgroups exhibit different navigational traits. Furthermore, we provide strong evidence that the semantic nature of the underlying folksonomy is an essential factor for explaining navigation.}, address = {New York, NY, USA}, author = {Niebler, Thomas and Becker, Martin and Zoller, Daniel and Doerfel, Stephan and Hotho, Andreas}, booktitle = {Proceedings of the 25th ACM International on Conference on Information and Knowledge Management}, publisher = {ACM}, series = {CIKM '16}, title = {FolkTrails: Interpreting Navigation Behavior in a Social Tagging System}, year = 2016 }
• Beutel, A.: Correlation of Subjective and Objective Measurements in Enterprise Networks, (2016).
  [ BibTeX ]