Adaptive Replication in Distributed Content Delivery Networks

We address the problem of content replication in large distributed content delivery networks, composed of a data center assisted by many small servers with limited capabilities and located at the edge of the network. The objective is to optimize the placement of contents on the servers to offload as much as possible the data center. We model the system constituted by the small servers as a loss network, each loss corresponding to a request to the data center. Based on large system / storage behavior, we obtain an asymptotic formula for the optimal replication of contents and propose adaptive schemes related to those encountered in cache networks but reacting here to loss events, and faster algorithms generating virtual events at higher rate while keeping the same target replication. We show through simulations that our adaptive schemes outperform significantly standard replication strategies both in terms of loss rates and adaptation speed.Comment: 10 pages, 5 figure

To Achieve An Optimal Tradeoff Between P2p Overlay Maintenance And Video Sharing Efficiency In Osn’s

Video sharing has been a gradually more popular application in OSNs facilitating users to share their personal videos or interesting videos they found with their friends. However OSN’s additional progress is strictly caught up by the inherent limits of the conventional client/server architecture of its video sharing system which is not only costly in terms of server storage and bandwidth but also not scalable with the high amount of users and video content in OSNs. The efforts have been dedicated to perk up the client/server architecture for video sharing with the peer-to-peer (P2P) architecture being the most promising. P2P-based video sharing has been used in on demand video streaming.The dimension reveals that mainly of the viewers of a user’s videos are the user’s close friends, most video views are driven by social relationships and the rest are driven by interests and viewers of the same video tend to live in the same location. Based on our observations we propose Social Tube a system that discover the social relationship interest resemblance and location to improve the presentation of video sharing in OSNs. Specifically an OSN has a social network (SN)-based P2P overlay construction algorithm that come together peers based on their social relationships and interests.

Supporting Non-Linear and Non-Continuous Media Access in Peer-to-Peer Multimedia Systems

Ph.DDOCTOR OF PHILOSOPH

Profiling Large-scale Live Video Streaming and Distributed Applications

PhDToday, distributed applications run at data centre and Internet scales, from intensive data analysis, such as MapReduce; to the dynamic demands of a worldwide audience, such as YouTube. The network is essential to these applications at both scales. To provide adequate support, we must understand the full requirements of the applications, which are revealed by the workloads. In this thesis, we study distributed system applications at different scales to enrich this understanding. Large-scale Internet applications have been studied for years, such as social networking service (SNS), video on demand (VoD), and content delivery networks (CDN). An emerging type of video broadcasting on the Internet featuring crowdsourced live video streaming has garnered attention allowing platforms such as Twitch to attract over 1 million concurrent users globally. To better understand Twitch, we collected real-time popularity data combined with metadata about the contents and found the broadcasters rather than the content drives its popularity. Unlike YouTube and Netflix where content can be cached, video streaming on Twitch is generated instantly and needs to be delivered to users immediately to enable real-time interaction. Thus, we performed a large-scale measurement of Twitchs content location revealing the global footprint of its infrastructure as well as discovering the dynamic stream hosting and client redirection strategies that helped Twitch serve millions of users at scale. We next consider applications that run inside the data centre. Distributed computing applications heavily rely on the network due to data transmission needs and the scheduling of resources and tasks. One successful application, called Hadoop, has been widely deployed for Big Data processing. However, little work has been devoted to understanding its network. We found the Hadoop behaviour is limited by hardware resources and processing jobs presented. Thus, after characterising the Hadoop traffic on our testbed with a set of benchmark jobs, we built a simulator to reproduce Hadoops job traffic With the simulator, users can investigate the connections between Hadoop traffic and network performance without additional hardware cost. Different network components can be added to investigate the performance, such as network topologies, queue policies, and transport layer protocols. In this thesis, we extended the knowledge of networking by investigated two widelyused applications in the data centre and at Internet scale. We (i)studied the most popular live video streaming platform Twitch as a new type of Internet-scale distributed application revealing that broadcaster factors drive the popularity of such platform, and we (ii)discovered the footprint of Twitch streaming infrastructure and the dynamic stream hosting and client redirection strategies to provide an in-depth example of video streaming delivery occurring at the Internet scale, also we (iii)investigated the traffic generated by a distributed application by characterising the traffic of Hadoop under various parameters, (iv)with such knowledge, we built a simulation tool so users can efficiently investigate the performance of different network components under distributed applicationQueen Mary University of Londo

Contributions à la réplication de données dans les systèmes distribués à grande échelle

Data replication is a key mechanism for building a reliable and efficient data management system. Indeed, by keeping several replicas for each piece of data, it is possible to improve durability. Furthermore, well-placed copies reduce data accesstime. However, having multiple copies for a single piece of data creates consistency problems when the data is updated. Over the last years, I made contributions related to these three aspects: data durability, data access performance and data consistency. RelaxDHT and SPLAD enhance data durability by placing data copies smartly. Caju, AREN and POPS reduce access time by improving data locality and by taking popularity into account. To enhance data lookup performance, DONUT creates efficient shortcuts taking data distribution into account. Finally, in the replicated database context, Gargamel parallelizes independent transactions only, improving database performance and avoiding aborting transactions. My research has been carried out in collaboration with height PhD students, four of which have defended. In my future work, I plan to extend these contributions by (i) designing a storage system tailored for MMOGs, which are very demanding, and (ii) designing a data management system that is able to re-distribute data automatically in order to scale the number of servers up and down according to the changing workload, leading to a greener data management.La réplication de données est une technique clé pour permettre aux systèmes de gestion de données distribués à grande échelle d'offrir un stockage fiable et performant. Comme il gère un nombre suffisant de copies de chaque donnée, le système peut améliorer la pérennité. De plus, la présence de copies bien placées réduit les temps d'accès. Cependant, cette même existence de plusieurs copies pose des problèmes de cohérence en cas de modification. Ces dernières années, mes contributions ont porté sur ces trois aspects liés à la réplication de données: la pérennité des données, la performance desaccès et la gestion de la cohérence. RelaxDHT et SPLAD permettent d'améliorer la pérennité des données en jouant sur le placement des copies. Caju, AREN et POPS permettent de réduire les temps d'accès aux données en améliorant la localité et en prenant en compte la popularité. Pour accélérer la localisation des copies, DONUT crée des raccourcis efficaces prenant en compte la distribution des données. Enfin, dans le contexte des bases de données répliquées,Gargamel permet de ne paralléliser que les transactions qui sont indépendantes, améliorant ainsi les performances et évitant tout abandon de transaction pour cause de conflit. Ces travaux ont été réalisés avec huit étudiants en thèse dont quatre ont soutenu. Pour l'avenir, je me propose d'étendre ces travaux, d'une part en concevant un système de gestion de données pour les MMOGs, une classe d'application particulièrement exigeante; et, d'autre part, en concevant des mécanismes de gestion de données permettant de n'utiliser que la quantité strictement nécessaire de ressources, en redistribuant dynamiquement les données en fonction des besoins, un pas vers une gestion plus écologique des données

The Road Ahead for Networking: A Survey on ICN-IP Coexistence Solutions

In recent years, the current Internet has experienced an unexpected paradigm shift in the usage model, which has pushed researchers towards the design of the Information-Centric Networking (ICN) paradigm as a possible replacement of the existing architecture. Even though both Academia and Industry have investigated the feasibility and effectiveness of ICN, achieving the complete replacement of the Internet Protocol (IP) is a challenging task. Some research groups have already addressed the coexistence by designing their own architectures, but none of those is the final solution to move towards the future Internet considering the unaltered state of the networking. To design such architecture, the research community needs now a comprehensive overview of the existing solutions that have so far addressed the coexistence. The purpose of this paper is to reach this goal by providing the first comprehensive survey and classification of the coexistence architectures according to their features (i.e., deployment approach, deployment scenarios, addressed coexistence requirements and architecture or technology used) and evaluation parameters (i.e., challenges emerging during the deployment and the runtime behaviour of an architecture). We believe that this paper will finally fill the gap required for moving towards the design of the final coexistence architecture.Comment: 23 pages, 16 figures, 3 table