| 1. |
- Beisert, Niklas, et al.
(författare)
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Review of AdS/CFT Integrability : An Overview
- 2012
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Ingår i: Letters in Mathematical Physics. - : Springer Science and Business Media LLC. - 0377-9017 .- 1573-0530. ; 99:1-3, s. 3-32
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Forskningsöversikt (refereegranskat)abstract
- This is the introductory chapter of a review collection on integrability in the context of the AdS/CFT correspondence. In the collection we present an overview of the achievements and the status of this subject as of the year 2010.
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| 2. |
- Borges Vieira, Alex, et al.
(författare)
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Characterizing SopCast Client Behavior
- 2012
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Ingår i: Computer Communications. - : Elsevier BV. - 0140-3664 .- 1873-703X. ; 35:8, s. 1004-1016
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Tidskriftsartikel (refereegranskat)abstract
- Live streaming media applications are becoming more popular each day. Indeed, some important TV channels already broadcast their live content on the Internet. In such scenario, Peer-to-Peer (P2P) applications are very attractive as platforms to distribute live content to large client populations at low costs. A thorough understanding of how clients of such applications typically behave, particularly in terms of dynamic patterns, can provide useful insights into the design of more cost-effective and robust solutions. With the goal of extending the current knowledge of how clients of live streaming applications typically behave, this paper provides a detailed characterization of clients of SopCast, a currently very popular P2P live streaming application. We have analyzed a series of SopCast transmissions collected using PlanetLab. These transmissions are categorized into two different types, namely, major event live transmissions and regular (or non-event) live transmissions. Our main contributions are: (a) a detailed model of client behavior in P2P live streaming applications, (b) the characterization of all model components for two different types of transmissions in the SopCast application, (c) the identification of qualitative and quantitative similarities and differences in the typical client behavior across different transmissions, and (d) the determination of parameter values for the proposed client behavior model to support the design of realistic synthetic workload generators.
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| 3. |
- Borges Vieira, Alex, et al.
(författare)
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SopCast P2P live streaming : live session traces and analysis
- 2013
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Ingår i: Proceedings of the 4th ACM Multimedia Systems Conference. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450318945 ; , s. 125-130
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Konferensbidrag (refereegranskat)abstract
- P2P-TV applications have attracted a lot of attention fromthe research community in the last years. Such systemsgenerate a large amount of data which impacts the networkperformance. As a natural consequence, characterizingthese systems has become a very important task to developbetter multimedia systems. However, crawling data fromP2P live streaming systems is particularly challenging bythe fact that most of these applications have privateprotocols. In this work, we present a set of logs from a verypopular P2P live streaming application, the SopCast. Wedescribe our crawling methodology, and present a briefSopCast characterization. We believe that our logs and thecharacterization can be used as a starting point to thedevelopment of new live streaming systems.
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| 4. |
- de Carvalho Gomes, Pedro, 1980-, et al.
(författare)
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Verification of P2P live streaming systems using symmetry-based semiautomatic abstractions
- 2012
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Ingår i: Proceedings of the 2012 International Conference on High Performance Computing and Simulation, HPCS 2012. - : IEEE. - 9781467323598 ; , s. 343-349
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Konferensbidrag (refereegranskat)abstract
- P2P systems are one of the most efficient data transport technologies in use today. Particularly, P2P live streaming systems have been growing in popularity recently. However, analyzing such systems is difficult. Developers are not able to realize a complete test due the due to system size and complex dynamic behavior. This may lead us to develop protocols with errors, unfair or even with low performance. One way of performing such an analysis is using formal methods. Model Checking is one such method that can be used for the formal verification of P2P systems. However it suffers from the combinatory explosion of states. The problem can be minimized with techniques such as abstraction and symmetry reduction. This work combines both techniques to produce reduced models that can be verified in feasible time. We present a methodology to generate abstract models of reactive systems semi-automatically, based on the model's symmetry. It defines modeling premises to make the abstraction procedure semiautomatic, i.e., without modification of the model. Moreover, it presents abstraction patterns based on the system symmetry and shows which properties are consistent with each pattern. The reductions obtained by the methodology were significant. In our test case of a P2P network, it has enabled the verification of liveness properties over the abstract models which did not finish with the original model after more than two weeks of intensive computation. Our results indicate that the use of model checking for the verification of P2P systems is feasible, and that our modeling methodology can increase the efficiency of the verification algorithms enough to enable the analysis of real complex P2P live streaming systems.
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