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  • 51.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Bergström, Patrik
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Eager, Derek
    University of Saskatchewan.
    Mahanti, Anirban
    NICTA, Sydney, Australia.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Empowering the creative user: personalized HTTP-based adaptive streaming of multi-path nonlinear video2013In: FhMN '13 Proceedings of the 2013 ACM SIGCOMM workshop on Future human-centric multimedia networking, New York, USA: Association for Computing Machinery (ACM), 2013, p. 53-58Conference paper (Refereed)
    Abstract [en]

    This paper presents the design, implementation, and validation of a novel system that supports streaming and playout of personalized, multi-path, nonlinear video. In contrast to regular video, in which the file content is played sequentially, our design allows multiple nonlinear video sequences of the underlying (linear) video to be stitched together and played in any personalized order, and clients can be provided multiple path choices. The design combines the ideas of HTTP-based adaptive streaming (HAS) and multi-path nonlinear video. Personalization of the content is achieved with the use of a customized metafile, which is downloaded separately from the underlying media and the manifest file that defines the HAS structure. An extension to the user interface allows path choices to be presented to and made by the user. Novel buffer management and prefetching policies are used to ensure seamless uninterrupted playback regardless of client path choices, even under scenarios in which clients defer their choices until the last possible moment. Our solution allows creative home users to easily create their own multi-path nonlinear video, opening the door to an endless possibility of new opportunities and media forms.

  • 52.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Eager, D.
    University of of Saskatchewan, Canada.
    Mahanti, A.
    NICTA, Australia.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Quality-adaptive prefetching for interactive branched video using HTTP-based Adaptive Streaming2014In: MM 2014 - Proceedings of the 2014 ACM Conference on Multimedia, Association for Computing Machinery, Inc , 2014, p. 317-326Conference paper (Refereed)
    Abstract [en]

    Interactive branched video that allows users to select their own paths through the video, provides creative content designers with great personalization opportunities; however, such video also introduces significant new challenges for the system developer. For example, without careful prefetching and buffer management, the use of multiple alternative playback paths can easily result in playback interruptions. In this paper, we present a full implementation of an interactive branched video player using HTTP-based Adaptive Streaming (HAS) that provides seamless playback even when the users defer their branch path choices to the last possible moment. Our design includes optimized prefetching policies that we derive under a simple optimization framework, effective buffer management of prefetched data, and the use of parallel TCP connections to achieve efficient buffer workahead. Through performance evaluation under a wide range of scenarios, we show that our optimized policies can effectively prefetch data of carefully selected qualities along multiple alternative paths such as to ensure seamless playback, offering users a pleasant viewing experience without playback interruptions.

  • 53.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Eager, Derek
    University of Saskatchewan, Canada.
    Mahanti, Anirban
    NICTA, Australia.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Bandwidth-aware Prefetching for Proactive Multi-video Preloading and Improved HAS Performance2015In: Proceedings of the ACM International Conference on Multimedia (ACM Multimedia), New York, USA: Association for Computing Machinery (ACM), 2015, p. 551-560Conference paper (Refereed)
    Abstract [en]

    This paper considers the problem of providing users playing one streaming video the option of instantaneous and seamless playback of alternative videos. Recommendation systems can easily provide a list of alternative videos, but there is little research on how to best eliminate the startup time for these alternative videos. The problem is motivated by services that want to retain increasingly impatient users, who frequently watch the beginning of multiple videos, before viewing a video to the end. We present the design, implementation, and evaluation of an HTTP-based Adaptive Streaming (HAS) solution that provides careful prefetching and buffer management. We also present the design and evaluation of three fundamental policy classes that provide different tradeoffs between how aggressively new alternative videos are prefetched versus the importance of ensuring high playback quality. We show that our solution allows us to reduce the startup times of alternative videos by an order of magnitude and effectively adapt the quality such as to ensure the highest possible playback quality of the video being viewed. By improving the channel utilization we also address the discrimination problem that HAS clients often suffer from, allowing us to in some cases simultaneously improve the playback quality of the video being viewed and provide the value-added service of allowing instantaneous playback of the prefetched alternative videos.

  • 54.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Eager, Derek
    University of Saskatchewan, Canada.
    Mahanti, Anirban
    NICTA, Australia.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Helping Hand or Hidden Hurdle: Proxy-assisted HTTP-based Adaptive Streaming Performance2013In: Modeling, Analysis & Simulation of Computer and Telecommunication Systems (MASCOTS), 2013 IEEE 21st International Symposium, IEEE , 2013, p. 182-191Conference paper (Refereed)
    Abstract [en]

    HTTP-based Adaptive Streaming (HAS) has become a widely-used video delivery technology. Use of HTTP enables relatively easy firewall/NAT traversal and content caching. While caching is an important aspect of HAS, there is not much public research on the performance impact proxies and their policies have on HAS. In this paper we build an experimental framework using open source Squid proxies and the most recent Open Source Media Framework (OSMF). A range of content-aware policies can be implemented in the proxies and tested, while the player software can be instrumented to measure performance as seen at the client. Using this framework, the paper makes three main contributions. First, we present a scenario-based performance evaluation of the latest version of the OSMF player. Second, we quantify the benefits using different proxy-assisted solutions, including basic best effort policies and more advanced content quality aware prefetching policies. Finally, we present and evaluate a cooperative framework in which clients and proxies share information to improve performance. In general, the bottleneck location and network conditions play central roles in which policy choices are most advantageous, as they significantly impact the relative performance differences between policy classes. We conclude that careful design and policy selection is important when trying to enhance HAS performance using proxy assistance.

  • 55. Lev-tov, Nissan
    et al.
    Carlsson, Niklas
    University of Calgary.
    Li, Zongpeng
    Williamson, Carey
    Zhang, Song
    Dynamic File-selection Policies for Bundling in BitTorrent-like Systems2010In: Proc. IEEE IWQoS ’10, IEEE , 2010, p. 1-9Conference paper (Refereed)
  • 56.
    Linder, Tova
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Persson, Pontus
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Forsberg, Anton
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Danielsson, Jakob
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    On Using Crowd-sourced Network Measurements for Performance Prediction2016In: Proc. IEEE/IFIP Wireless On-demand Network Systems and Services Conference (IEEE/IFIP WONS), Cortina d'Ampezzo, Italy, Jan. 2016., IEEE Computer Society Digital Library, 2016, p. 1-8Conference paper (Refereed)
    Abstract [en]

    Geo-location-based bandwidth prediction together with careful download scheduling for mobile clients can be used to minimize download times, reduce energy usage, and improve streaming performance. Although crowd-sourced measurements provide an important prediction tool, little is known about the prediction accuracy and improvements such datasets can provide. In this paper we use a large-scale crowd-sourced dataset from Bredbandskollen, Sweden's primary speedtest service, to evaluate the prediction accuracy and achievable performance improvements with such data. We first present a scalable performance map methodology that allows fast insertion/retrieval of geo-sparse measurements, and use this methodology to characterize the Bredbandskollen usage. Second, we analyze the bandwidth variations and predictability of the download speeds observed within and across different locations, when accounting for various factors. Third, we evaluate the relative performance improvements achievable by users leveraging different subsets of measurements (capturing effects of limited sharing or filtering based on operator, network technology, or both) when predicting opportune locations to perform downloads. Our results are encouraging for both centralized and peer-to-peer performance map solutions. For example, most measurements are done in locations with many measurements and good prediction accuracy, and further improvements are possible through filtering (e.g., based on operator and technology) or limited information sharing.

  • 57.
    Ljung, Dennis
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Lambrix, Patrick
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Player Pairs Valuation in Ice Hockey2018In: Proceedings of the 5th Workshop on Machine Learning and Data Mining for Sports Analytics: co-located with 2018 European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML PKDD 2018) / [ed] Ulf Brefeld, Jesse Davis, Jan Van Haaren, Albrecht Zimmermann, Cham: Springer, 2018, Vol. 11330, p. 82-92Conference paper (Refereed)
    Abstract [en]

    To overcome the shortcomings of simple metrics for evaluating player performance, recent works have introduced more advanced metrics that take into account the context of the players’ actions and perform look-ahead. However, as ice hockey is a team sport, knowing about individual ratings is not enough and coaches want to identify players that play particularly well together. In this paper we therefore extend earlier work for evaluating the performance of players to the related problem of evaluating the performance of player pairs. We experiment with data from seven NHL seasons, discuss the top pairs, and present analyses and insights based on both the absolute and relative ice time together.

  • 58.
    Mahanti, Aniket
    et al.
    University of Auckland, New Zealand.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Arlitt, Martin
    University of Calgary, Canada.
    Williamson, Carey
    University of Calgary, Canada.
    Characterizing Cyberlocker Traffic Flows2012In: IEEE Conference on Local Computer Networks (LCN) 2012, IEEE , 2012, p. 410-418Conference paper (Refereed)
    Abstract [en]

    Cyberlockers have recently become a very popular means of distributing content. Today, cyberlocker traffic accounts for a non-negligible fraction of the total Internet traffic volume, and is forecasted to grow significantly in the future. The underlying protocol used in cyberlockers is HTTP, and increased usage of these services could drastically alter the characteristics of Web traffic. In light of the evolving nature of Web traffic, updated traffic models are required to capture this change. Despite their popularity, there has been limited work on understanding the characteristics of traffic flows originating from cyberlockers. Using a year-long trace collected from a large campus network, we present a comprehensive characterization study of cyberlocker traffic at the transport layer. We use a combination of flow-level and host-level characteristics to provide insights into the behavior of cyberlockers and their impact on networks. We also develop statistical models that capture the salient features of cyberlocker traffic. Studying the transport-layer interaction is important for analyzing reliability, congestion, flow control, and impact on other layers as well as Internet hosts. Our results can be used in developing improved traffic simulation models that can aid in capacity planning and network traffic management.

  • 59.
    Mahanti, Aniket
    et al.
    University of Calgary, Canada.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Mahanti, Anirban
    NICTA, Eveleigh, New South Wales, Australia.
    Arlitt, Martin
    University of Calgary, Canada.
    Williamson, Carey
    University of Calgary, Canada.
    A Tale of the Tails: Power-laws in Internet Measurements2013In: IEEE Network, ISSN 0890-8044, E-ISSN 1558-156X, Vol. 27, no 1, p. 59-64Article in journal (Refereed)
    Abstract [en]

    Power-laws are ubiquitous in the Internet and its applications. In this survey article, we provide a review of such properties in Internet measurements. First, we give definitions of power-law distributions, such as Pareto and Zipf, while also reviewing heavy tails and long tails, and discussing a well-known model for understanding power-law behaviour in computer networks. Second, we present several examples of Internet workload properties exhibiting power-law behaviour. Finally, we explore several implications of power-law in computer networks. Using examples from past and present, we review how researchers have studied and exploited power-law properties. We observe that despite the challenges posed, power-laws have been effectively leveraged by researchers to improve the design and performance of Internet-based systems.

  • 60.
    Mahanti, Aniket
    et al.
    University of Calgary, Canada.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Williamson, Carey
    University of Calgary, Canada.
    Content Sharing Dynamics in the Global File Hosting Landscape2012In: Proc. IEEE International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems (MASCOTS 2012, IEEE , 2012, p. 219-228Conference paper (Refereed)
    Abstract [en]

    We present a comprehensive longitudinal characterization study of the dynamics of content sharing in the global file hosting landscape. We leverage datasets collected from multiple vantage points that allow us to understand how usage of these services evolve over time and how traffic is directed into and out of these sites. We analyze the characteristics of hosted content in the public domain, and investigate the dissemination mechanisms of links. To the best of our knowledge, this is the largest detailed characterization study of the file hosting landscape from a global viewpoint.

  • 61.
    Mahanti, Aniket
    et al.
    University of Calgary, Canada.
    Carlsson, Niklas
    University of Calgary, Canada.
    Williamson, Carey
    University of Calgary, Canada.
    Arlitt, Martin
    University of Calgary, Canada.
    Ambient Interference Effects in Wi-Fi Networks2010In: NETWORKING 2010: 9th International IFIP TC 6 Networking Conference, Chennai, India, May 11-15, 2010. Proceedings / [ed] Mark Crovella, Laura Marie Feeney, Dan Rubenstein and S. V. Raghavan, Springer Berlin/Heidelberg, 2010, p. 160-173Chapter in book (Refereed)
    Abstract [en]

    This paper presents a measurement study of interference from six common devices that use the same 2.4 GHz ISM band as the IEEE 802.11 protocol. Using both controlled experiments and production environment measurements, we quantify the impact of these devices on the performance of 802.11 Wi-Fi networks. In our controlled experiments, we characterize the interference properties of these devices, as well as measure and discuss implications of interference on data, video, and voice traffic. Finally, we use measurements from a campus network to understand the impact of interference on the operational performance of the network. Overall, we find that the campus network is exposed to a large variety of non-Wi-Fi devices, and that these devices can have a significant impact on the interference level in the network.

  • 62. Mahanti, Aniket
    et al.
    Williamson, Carey
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques.
    Characterizing the File Hosting Service Ecosystem2010In: Proc. ACM CoNEXT Student Workshop (CoNEXT ’10), New York, USA: ACM , 2010, p. 3:1-3:2Conference paper (Refereed)
    Abstract [en]

    File Hosting Services (FHS) such as Rapidshare and Mega-upload have recently become popular. The decline of P2P file sharing has prompted various services including FHS to replace it. We propose a comprehensive multi-level characterization of the FHS ecosystem. We devise a measurement framework to collect datasets from multiple vantage points. To the best of our knowledge, this work is the first to characterize the FHS ecosystem. The work will highlight the content, usage, performance, infrastructure, and quality of service characteristics of FHS. FHS can have significant implications on Internet traffic, if these services were to supplant P2P as the dominant content sharing technology.

  • 63.
    Mahanti, Aniket
    et al.
    University of Calgary.
    Williamson, Carey
    University of Calgary.
    Carlsson, Niklas
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, Database and information techniques.
    Arlitt, Martin
    University of Calgary.
    Mahanti, Anirban
    NICTA, Australia .
    Characterizing the file hosting ecosystem: A view from the edge2011In: Performance evaluation (Print), ISSN 0166-5316, E-ISSN 1872-745X, Vol. 68, no 11, p. 1085-1102Article in journal (Refereed)
    Abstract [en]

    We present a comprehensive, longitudinal characterization study of the file hosting ecosystem using HTTP traces collected from a large campus network over a one-year period. We performed detailed multi-level analysis of the usage behavior, infrastructure properties, content characteristics, and user-perceived performance of the top five services in terms of traffic volume, namely RapidShare, Megaupload, zSHARE, MediaFire, and Hotfile. We carefully devised methods to identify user clickstreams in the HIP traces, including the identification of free and premium user instances, as well as the identification of content that is split into multiple pieces and downloaded using multiple transactions. Throughout this characterization, we compare and contrast these services with each other as well as with peer-to-peer file sharing and other media sharing services.

  • 64. Mitra, Siddharth
    et al.
    Agrawal, Mayank
    Yadav, Amit
    Carlsson, Niklas
    University of Calgary.
    Eager, Derek
    Mahanti, Anirban
    Characterizing Web-based Video Sharing Workloads2009In: Proc. International World Wide Web Conference (WWW ’09), Madrid, Spain, April 2009, 2009, p. 1191-1192Conference paper (Refereed)
  • 65.
    Mitra, Siddharth
    et al.
    Indian Institute Technology Delhi.
    Agrawal, Mayank
    Indian Institute Technology Delhi.
    Yadav, Amit
    Indian Institute Technology Delhi.
    Carlsson, Niklas
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, Database and information techniques.
    Eager, Derek
    University of Saskatchewan.
    Mahanti, Anirban
    NICTA.
    Characterizing Web-Based Video Sharing Workloads2011In: ACM TRANSACTIONS ON THE WEB, ISSN 1559-1131, Vol. 5, no 2Article in journal (Refereed)
    Abstract [en]

    Video sharing services that allow ordinary Web users to upload video clips of their choice and watch video clips uploaded by others have recently become very popular. This article identifies invariants in video sharing workloads, through comparison of the workload characteristics of four popular video sharing services. Our traces contain metadata on approximately 1.8 million videos which together have been viewed approximately 6 billion times. Using these traces, we study the similarities and differences in use of several Web 2.0 features such as ratings, comments, favorites, and propensity of uploading content. In general, we find that active contribution, such as video uploading and rating of videos, is much less prevalent than passive use. While uploaders in general are skewed with respect to the number of videos they upload, the fraction of multi-time uploaders is found to differ by a factor of two between two of the sites. The distributions of lifetime measures of video popularity are found to have heavy-tailed forms that are similar across the four sites. Finally, we consider implications for system design of the identified invariants. To gain further insight into caching in video sharing systems, and the relevance to caching of lifetime popularity measures, we gathered an additional dataset tracking views to a set of approximately 1.3 million videos from one of the services, over a twelve-week period. We find that lifetime popularity measures have some relevance for large cache (hot set) sizes (i.e., a hot set defined according to one of these measures is indeed relatively "hot"), but that this relevance substantially decreases as cache size decreases, owing to churn in video popularity.

  • 66.
    Nadim Parvez, Khandoker
    et al.
    North South University, Bangladesh .
    Williamson, Carey
    University of Calgary, Canada .
    Mahanti, Anirban
    National ICT Australia NICTA, Australia .
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Insights on Media Streaming Progress Using BitTorrent-Like Protocols for On-Demand Streaming2012In: IEEE/ACM Transactions on Networking, ISSN 1063-6692, E-ISSN 1558-2566, Vol. 20, no 3, p. 637-650Article in journal (Refereed)
    Abstract [en]

    This paper develops analytical models that characterize the behavior of on-demand stored media content delivery using BitTorrent-like protocols. The models capture the effects of different piece selection policies, including Rarest-First, two variants of In-Order, and two probabilistic policies (Portion and Zipf). Our models provide insight into system behavior and help explain the sluggishness of the system with In-Order streaming. We use the models to compare different retrieval policies across a wide range of system parameters, including peer arrival rate, upload/download bandwidth, and seed residence time. We also provide quantitative results on the startup delays and retrieval times for streaming media delivery. Our results provide insights into the design tradeoffs for on-demand media streaming in peer-to-peer networks. Finally, the models are validated using simulations.

  • 67.
    Nsolo, Edward
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Lambrix, Patrick
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Player Valuation in European Football2019In: Proceedings of the 5th Workshop on Machine Learning and Data Mining for Sports Analytics: co-located with 2018 European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML PKDD 2018) / [ed] Ulf Brefeld, Jesse Davis, Jan Van Haaren, Albrecht Zimmermann, Cham: Springer, 2019, Vol. 11330, p. 42-54Conference paper (Refereed)
    Abstract [en]

    As the success of a team depends on the performance of individual players, the valuation of player performance has become an important research topic. In this paper, we compare and contrast which attributes and skills best predict the success of individual players in their positions in five European top football leagues. Further, we evaluate different machine learning algorithms regarding prediction performance. Our results highlight features distinguishing top-tier players and show that prediction performance is higher for forwards than for other positions, suggesting that equally good prediction of defensive players may require more advanced metrics.

  • 68.
    Nykvist, Carl
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Sjöström, Linus
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Gustafsson, Josef
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Server-Side Adoption of Certificate Transparency2018In: Passive and Active Measurement: 19th International Conference, PAM 2018, Berlin, Germany, March 26–27, 2018, Proceedings / [ed] Robert Beverly, Georgios Smaragdakis, Anja Feldmann, Cham: Springer, 2018, Vol. 10771, p. 186-199Conference paper (Refereed)
    Abstract [en]

    Certificate Transparency (CT) was developed to mitigate shortcomings in the TLS/SSL landscape and to assess the trustworthiness of Certificate Authorities (CAs) and the certificates they create. With CT, certificates should be logged in public, audible, append-only CT logs and servers should provide clients (browsers) evidence, in the form of Signed Certificate Timestamps (SCTs), that the certificates that they present have been logged in credible CT logs. These SCTs can be delivered using three different methods: (i) X.509v3 extension, (ii) TLS extension, and (iii) OSCP stapling. In this paper, we develop a client-side measurement tool that implements all three methods and use the tool to analyze the SCT adoption among the one-million most popular web domains. Using two snapshots (from May and Oct. 2017), we answer a wide range of questions related to the delivery choices made by different domains, identify differences in the certificates used by these domains, the CT logs they use, and characterize the overheads and potential performance impact of the SCT delivery methods. By highlighting some of the tradeoffs between the methods and differences in the websites selecting them, we provide insights into the current SCT adoption status and differences in how domains have gone upon adopting this new technology.

  • 69. Parvez, Nadim
    et al.
    Williamson, Carey
    Mahanti, Anirban
    Carlsson, Niklas
    University of Saskatchewan.
    Analysis of BitTorrent-like Protocols for On-demand Stored Media Streaming2008In: Proc. ACM SIGMETRICS ’08, ACM , 2008, p. 301-312Conference paper (Refereed)
  • 70.
    Sans Fuentes, Carles
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Lambrix, Patrick
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Player impact measures for scoring in ice hockey2019In: Proceedings of MathSport International 2019 Conference / [ed] Dimitris Karlis, Ioannis Ntzoufras, Sotiris Drikos, Athen: Athens University of Economics and Business , 2019, p. 307-317Conference paper (Refereed)
    Abstract [en]

    A commonly used method to evaluate player performance is to attribute values to the different actions that players perform and sum up these values every time a player performs these actions. In ice hockey, such metrics include the number of goals, assists, points, plus-minus statistics and recently Corsi and Fenwick. However, these metrics do not capture the context of player actions and the impact they have on the outcome of later actions. Therefore, recent works have introduced more advanced metrics that take into account the context of the actions and perform look-ahead. The use of look-ahead is particularly valuable in low-scoring sports such as ice hockey. In this paper, we first extend a recent approach based on reinforcement learning for measuring a player's impact on a team's scoring. Second, using NHL play-by-play data for several regular seasons, we analyze and compare these and other traditional measures of player impact. Third, we introduce notions of streaks and show that these may provide information about good players, but do not provide a good predictor for the impact that a player will have the next game. Finally, streaks are compared for different player categories, highlighting differences between player positions and correlations with player salaries.

  • 71.
    Stokes, Klara
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    A Peer-to-Peer Agent Community for Digital Oblivion in Online Social Networks2013In: Privacy, Security and Trust (PST), 2013 Eleventh Annual International Conference, Institute of Electrical and Electronics Engineers (IEEE), 2013, p. 103-110Conference paper (Refereed)
    Abstract [en]

    A long list of personal tragedies, including teenage suicides, has raised the importance of managing the personal information available on the Internet. It has been argued that it should be allowed to make mistakes, and that there should be a right to be forgotten. Unfortunately, today's Internet architecture and services typically do not support such functionality. We design a system that provides digital oblivion for users of online social networks. Participants form a peer-based agent community, which agree on protecting the privacy of individuals who request images to be forgotten. The system distributes and maintains up-to-date information on oblivion requests, and implements a filtering functionality when accessing an underlying online social network. We describe digital oblivion in terms of authentication of user-to-content relations and identify two user-to-content relations that are particularly relevant for digital oblivion. Finally, we design a family of protocols that provide digital oblivion with respect to these user-to-content relations, within the community that are implementing the protocol. Our protocols leverage a combination of digital signatures, watermarking, image tags, and trust management. No collaboration is required from the social network provider, although the system could also be incorporated as a standard feature of the social network.

  • 72.
    Vapen, Anna
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Mahanti, A.
    NICTA, Sydney NSW, Australia.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Third-party identity management usage on the web2014In: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Springer Berlin/Heidelberg, 2014, Vol. 8362 LNCS, p. 151-162Conference paper (Refereed)
    Abstract [en]

    Many websites utilize third-party identity management services to simplify access to their services. Given the privacy and security implications for end users, an important question is how websites select their third-party identity providers and how this impacts the characteristics of the emerging identity management landscape seen by the users. In this paper we first present a novel Selenium-based data collection methodology that identifies and captures the identity management relationships between sites and the intrinsic characteristics of the websites that form these relationships. Second, we present the first large-scale characterization of the third-party identity management landscape and the relationships that makes up this emerging landscape. As a reference point, we compare and contrast our observations with the somewhat more understood third-party content provider landscape. Interesting findings include a much higher skew towards websites selecting popular identity provider sites than is observed among content providers, with sites being more likely to form identity management relationships that have similar cultural, geographic, and general site focus. These findings are both positive and negative. For example, the high skew in usage places greater responsibility on fewer organizations that are responsible for the increased information leakage cost associated with highly aggregated personal information, but also reduces the users control of the access to this information. © 2014 Springer International Publishing Switzerland.

  • 73.
    Vapen, Anna
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Mahanti, Anirban
    NICTA, Australia.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    A Look at the Third-Party Identity Management Landscape2016In: IEEE Internet Computing, ISSN 1089-7801, E-ISSN 1941-0131, Vol. 20, no 2, p. 18-25Article in journal (Refereed)
    Abstract [en]

    Many websites act as relying parties (RPs) by allowing access to their services via third-party identity providers (IDPs), such as Facebook and Google. Using IDPs simplifies account creation, login activity, and information sharing across websites. However, different websites use of IDPs can have significant security and privacy implications for users. Here, the authors provide an overview of third-party identity managements current landscape. Using datasets collected through manual identification and large-scale crawling, they answer questions related to which sites act as RPs, which sites are the most successful IDPs, and how different classes of RPs select their IDPs.

  • 74.
    Vapen, Anna
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Mahanti, Anirban
    NICTA, Australia.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Information Sharing and User Privacy in the Third-party Identity Management Landscape2015In: ICT Systems Security and Privacy Protection: 30th IFIP TC 11 International Conference, SEC 2015, Hamburg, Germany, May 26-28, 2015, Proceedings / [ed] Hannes Federrath, Dieter Gollmann, Springer, 2015, p. 174-188Conference paper (Refereed)
    Abstract [en]

    The cross-site information sharing and authorized actions of third-party identity management can have significant privacy implications for the users. In this paper, we use a combination of manual analysis of identified third-party identity management relationships and targeted case studies to (i) capture how the protocol usage and third-party selection is changing, (ii) profile what information is requested to be shared (and actions to be performed) between websites, and (iii) identify privacy issues and practical problems that occur when using multiple accounts (associated with these services). By characterizing and quantifying the third-party relationships based on their cross-site information sharing, the study highlights differences in the privacy leakage risks associated with different classes of websites, and provides concrete evidence for how the privacy risks are increasing. For example, many news and file/video-sharing sites ask users to authorize the site to post information to the third-party website. We also observe a general increase in the breadth of information that is shared across websites, and find that due to usage of multiple third-party websites, in many cases, the user can lose (at least) partial control over which identities they can merge/relate and the information that is shared/posted on their behalf.

  • 75.
    Vapen, Anna
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Mahanti, Anirban
    NICTA, Australia.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, IISLAB - Laboratory for Intelligent Information Systems. Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Information Sharing and User Privacy in the Third-party Identity Management Landscape2015In: Proc. ACM Conference on Data and Application Security and Privacy (ACM CODASPY), ACM Digital Library, 2015, p. 151-153Conference paper (Refereed)
    Abstract [en]

    Third-party identity management services enable cross-site information sharing, making Web access seamless but also raise significant privacy implications for the users. Using a combination of manual analysis of identified third-party identity management relationships and targeted case studies we capture how the protocol usage and third-party selection is changing, profile what information is requested to be shared (and actions to be performed) between websites, and identify privacy issues and practical problems that occur when using multiple accounts (associated with these services). The study highlights differences in the privacy leakage risks associated with different classes of websites, and shows that the use of multiple third-party websites, in many cases, can cause the user to lose (at least) partial control over which information is shared/posted on their behalf.

  • 76.
    Vapen, Anna
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Longitudinal Analysis of the Third-party Authentication Landscape2016Conference paper (Refereed)
    Abstract [en]

    Many modern websites offer single sign-on (SSO) services, which allow the user to use an existing account with a third-party website such as Facebook to authenticate. When using SSO the user must approve an app-rights agreement that specifies what data related to the user can be shared between the two websites and any actions (e.g., posting comments) that the origin website is allowed to perform on behalf of the user on the third-party provider (e.g., Facebook). Both cross-site data sharing and actions performed on behalf of the user can have significant privacy implications. In this paper we present a longitudinal study of the third-party authentication landscape, its structure, and the protocol usage, data sharing, and actions associated with individual third-party relationships. The study captures the current state, changes in the structure, protocol usage, and information leakage risks.

  • 77.
    Varghese, Benoy
    et al.
    NICTA and University of New South Wales (UNSW), Australia.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Jourjon, Guillaume
    NICTA, Sydney, Australia.
    Mahanti, Anirban
    NICTA, Sydney, Australia.
    Shenoy, Prashant
    University of Massachusetts, USA.
    Greening Web Servers: A Case for Ultra Low-power Web Servers2014In: Proc. International Green Computing Conference (IGCC), IEEE Press, 2014Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate the feasibility of running web servers on low-power micro-computing boards, with emphasis on analysing the tradeoffs between power and performance. Today, small-to-medium scale enterprises, NGOs, universities typically deploy an architecture where frontend servers deliver static content and backend servers the dynamic content.   Experimentation using an ARM-based Raspberry Pi system shows that, for static content, Raspberry Pi achieves similar response times to that of a typical tower server running on standard hardware.   Although, the Raspberry Pi is found unsuitable for serving dynamic content, our findings show that many of these small-to-medium scale organisations can achieve large energy savings by using low-power servers for serving the static content.

  • 78.
    Williamson, Carey
    et al.
    University of Calgary, Canada.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    On Zipf Models for Probabilistic Piece Selection in P2P Stored Media Streaming2013In: IEEE International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems (MASCOTS), 2013, Institute of Electrical and Electronics Engineers (IEEE), 2013, p. 161-171Conference paper (Refereed)
    Abstract [en]

    The Zipf distribution is widely used to model Web site popularity, video popularity, and file referencing behavior. In recent published work, we proposed and evaluated a Zipf-based policy for probabilistic piece selection in Peer-to-Peer (P2P) media streaming. In this current paper, we revisit this Zipf model in more detail, and identify two fundamentally different modeling approaches, namely regenerative versus degenerative Zipf models. We illustrate the differences between the two models, provide refined analytical models for each, and validate the models with simulations in the context of P2P media streaming. The results show that the regenerative model is more appropriate for P2P streaming, because of its stronger sequential progress.

  • 79.
    Zhang, Song
    et al.
    University of Calgary, Canada.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Eager, Derek
    University of Saskatchewan, Canada.
    Li, Zongpeng
    University of Calgary, Canada.
    Mahanti, Anirban
    NICTA, Australia.
    Dynamic File Bundling for Large-scale Content Distribution2012In: IEEE Conference on Local Computer Networks (LCN) 2012, IEEE , 2012, p. 601-609Conference paper (Refereed)
    Abstract [en]

    One highly-scalable approach to content delivery is to harness the upload bandwidth of the clients. Peer-assisted content delivery systems have been shown to effectively offload the servers of popular files, as the request rates of popular content enable the formation of self-sustaining torrents, where the entire content of the file is available among the peers themselves. However, for less popular files, these systems are less helpful in offloading servers. With a long tail of mildly popular content, with a high aggregate demand, a large fraction of the file requests must still be handled by servers. In this paper, we present the design, implementation, and evaluation of a dynamic file bundling system, where peers are requested to download content which they may not otherwise download in order to "inflate" the popularity of less popular files. Our system introduces the idea of a super bundle, which consists of a large catalogue of files. From this catalogue, smaller bundles, consisting of a small set of files, can dynamically be assigned to individual users. The system can dynamically adjust the number of downloaders of each file and thus enables the popularity inflation to be optimized according to current file popularities and the desired tradeoff between download times and server resource usage. The system is evaluated on PlanetLab.

  • 80.
    Zhang, Song
    et al.
    University of Calgary Canada.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Eager, Derek
    University of Saskatchewan, Canada.
    Li, Zongpeng
    University of Calgary Canada.
    Mahanti, Anirban
    NICTA, Australia.
    Towards a Dynamic File Bundling System for Large-scale Content Distribution2011In: Modeling, Analysis and Simulation of Computer and Telecommunication Systems (MASCOTS 2011), 2011, p. 472-474Conference paper (Refereed)
    Abstract [en]

    Peer-assisted content delivery systems can provide scalable download service for popular files. For mildly popular content, however, these systems are less helpful in offloading servers as the request rate for less popular files may not enable formation of self-sustaining torrents (where the entire content of the file is available among the peers themselves). As there typically is a long tail of mildly popular content, with a high aggregate demand, a large fraction of the file requests must still be handled by servers, and is not off-loadable to peers. Bundling approaches have been proposed where peers are requested to download content which they may not otherwise be interested in order to ``inflate'' the popularity of less popular files. We present the design and implementation of a dynamic bundling system, in which a large number of files may be bundled to form a super bundle. From this super bundle, smaller individual bundles, consisting of a small set of files, can dynamically be assigned to individual users. Our system has the capability to dynamically adjust the number of downloaders of each file, thus allowing popularity inflation to be optimized according to current file popularities.

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