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Size Does Matter (in P2P Live Streaming)

Size Does Matter (in P2P Live Streaming)

Size Does Matter in P2P Live Streaming 7 c is big enough (all other parameters being the same), we can assume that more and more control messages per chunk can be exchanged between peers. This should achieve a proper diffusion, provided enough bandwidth is available, since a sender peer will have enough time to find a neighbor needing a given chunk. On the contrary, when c/s is too small, peers do not have enough time to ex- change control messages, resulting in missing chunks. Note that increasing m slightly improves the performance.

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On Using Seeders for P2P Live Streaming

On Using Seeders for P2P Live Streaming

1.1 Motivation In order to increase the available resources, a standard P2P technique is to leverage the capacity of the system by using seeders, i.e. peers that contribute to the system but are (currently) not needing anything. Using seeders is quite natural for file-sharing or Video-on-Demand: after a peer has downloaded its file or video, it becomes a potential seeder for that content. However, it is counter-intuitive live streaming systems: “live” content is created on the fly, so it cannot be pro-actively possessed by peers. Therefore, for a peer to act as a seeder, it has to receive at least a part of the corresponding content, which it does not want to watch by definition.
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Live seeding: Performance bounds of seeders for P2P live streaming

Live seeding: Performance bounds of seeders for P2P live streaming

D. About delays We do not have taken delay issues into account. The diffusion delay is obviously a major concern in the design of a live streaming system. However, it should be noted that the two heuristics we proposed are based on diffusion trees. Therefore the induced delay is at most equal to the delay of a single connection times a logarithm of NL . This is exactly the same type of delay that is experienced for diffusion based on leechers only, so we argue that using seeders should not impact the delay performance of a P2P live streaming system.

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On Resource Aware Algorithms in Epidemic Live Streaming

On Resource Aware Algorithms in Epidemic Live Streaming

significant benefit. In [15] a game-theoretic framework is proposed to model and evaluate incentive-based strategies to stimulate user cooperation. 1.2 Contribution In Section 2, we propose a model for unstructured P2P live streaming diffusion schemes that takes explicitly the awareness-agnostism trade-off into account. This model is highly versatile, so it can represent several existing resource- aware peer selection policies, as well as new ones. Then in Section 3.1 we propose recursive formulas for the diffusion function of a generic resource aware peer/latest blind chunk selection scheme. Lastly, by means of simulations, we deeply analyze in Section 4 the awareness-agnostic trade-off and the critical role the source policy plays in the system performance.
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The Structured Way of Dealing with Heterogeneous Live Streaming Systems

The Structured Way of Dealing with Heterogeneous Live Streaming Systems

Table 1: Summary of the main variables and terminologies used in this work. video live streaming: unstructured and structured, even if hybrid solutions are also possible [3]. In unstructured overlay networks, peers self organize themselves in an overlay network, that does not have a defined topology. CoolStreaming/DONet [4] is an implementation of this approach. In structured overlay networks, peers are organized in a static structure with the source at the root of the tree. There are many techniques used in P2P live streaming with single-source and structured topology. These techniques may fall into two categories: single-tree and multiple-tree. In the single-tree approach each node is connected to a small number of nodes to which it is responsible for providing the data stream. ZIGZAG [5] is an example of this approach. In the multiple-tree approach the main idea is to stripe the content across a forest of multicast trees where each node is a leaf in every tree except one, as done by SplitStream [6].
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Mesh-based overlay enhancing live video quality in pull-based P2P systems

Mesh-based overlay enhancing live video quality in pull-based P2P systems

overlay are connected via logical links, each of which is over paths in the underlying network. The overlay is constructed by providing for each system peer a set of peers watching the requested video, called neighbors. The peer can either pull the required chunks from its neighbors or push the chunks it has to them. In the pull approach [3] (respectively push [4]), the peer applies a chunk-scheduling mechanism to choose the chunks to be requested (resp. send) and its senders (resp. receivers) among the neighbors. The challenges to ensure the live video service performance metrics depend on some functioning constraints. Firstly, the peer start-up delay depends on the reception rate of the first chunks to be requested. It can be reduced by efficiency selecting these chunk senders. Secondly, the peer play-out delay depends on its neighbor‟s play-out delay. It may be reduced by requesting the chunks from the neighbor that has the lowest play-out delay. Thirdly, the video quality depends on the percentage of chunks successfully received before their displaying deadline. In P2P systems the video quality can be disrupted for two reasons. Firstly, chunks that are not received on time because either the jitter is unbounded or the recovery processing of packet losses takes too much time. Secondly, the unpredictable behavior of the system peers. A peer can leave the system at any moment which increases the chunk loss rate in the receiver peers. The P2P live streaming systems challenge is thus to design an
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The Structured Way of Dealing with Heterogeneous Live Streaming Systems

The Structured Way of Dealing with Heterogeneous Live Streaming Systems

The Structured Way of Dealing with Heterogeneous Live Streaming Systems 3 There are two main categories of distributed systems for video live stream- ing: unstructured and structured. [14] provides an overview of P2P based live streaming services. Hybrid solutions are also possible [22]. In unstructured overlay networks, peers self organize themselves in an overlay network, that does not have a defined topology. CoolStreaming/DONet [23] is an imple- mentation of this approach. In structured overlay networks, peers are orga- nized in a static structure with the source at the root of the tree. There are many techniques used in P2P live streaming with single-source and struc- tured topology. These techniques may fall into two categories: single-tree and multiple-tree. In the single-tree approach, each node is connected to a small number of nodes to which it is responsible for providing the data stream. ZIGZAG [20] is an implementation of this approach. In the multiple-tree ap- proach, the main idea is to stripe the content across a forest of multicast trees where each node is a leaf in every tree except one. SplitStream [7] is an implementation of this approach.
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Peer-to-peer live streaming for massively multiplayer online games

Peer-to-peer live streaming for massively multiplayer online games

III. D EMONSTRATION The scalability of the CNG P2P system and its robustness to peer churn were successfully tested using the ns-2 simulator with up to 1500 peers. An online version of the system was integrated in The Missing Ink [5] MMOG and is currently in the Alpha testing phase. A large scale Beta testing will be conducted with The Missing Ink gamers in the summer of 2012. Figure 3 shows a snapshot of the screen of an Alpha tester during an online live streaming session. The tester is using the P2P system to watch three live streams while playing the game. The demonstration at the P2P’12 conference will use four computers and the available Internet connection to illustrate how a user can advertise a live stream, capture and stream a video of the game, and watch up to three simultaneous live streams while playing The Missing Ink game. Ten live videos will also be streamed from CNG consortium members located in Leicester, London, Patras, Tel Aviv, and Brest. In addition, a number of live videos from regular The Missing Ink gamers will be available.
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Level-based peer-to-peer live streaming with rateless codes

Level-based peer-to-peer live streaming with rateless codes

In addition, from discussions with stakeholders in the Inter- net TV and gaming communities, we have identified another requirement, which has not been addressed in previous P2P works. The idea is that peers are arranged in levels such that live video is delivered at the same time to all peers in the same level. Moreover, peers in a higher level should be able to watch the video before those in a lower level. This level-based model is a generic way to implement a number of practical features: • in a tiered or freemium service (two popular business models where users are charged according to the quality
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Study of Repair Protocols for Live Video Streaming Distributed Systems

Study of Repair Protocols for Live Video Streaming Distributed Systems

P2P networks are of two types, with structured or un- structured overlays. In the first type, the nodes are organized according to a (or several) logical tree(s), called diffusion tree(s). The source of the video is the root and the video is distributed from the source to the leaves, fathers forwarding the video to their children. In an unstructured overlay, the tree is not explicitly defined: a node having chunks of the video forwards opportunistically these chunks to nodes who miss them. This second type of systems are the most frequently used as they handle very easily churn, i.e., the departure and arrival of users, which are very frequent in live video systems. Frequent churn is the main problem of live distributed streaming system and the main difference from classical mul- ticast systems. Structured overlays have the disadvantage that churn breaks their diffusion trees. However, we have hints that
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DASH in Twitch: Adaptive Bitrate Streaming in Live Game Streaming Platforms

DASH in Twitch: Adaptive Bitrate Streaming in Live Game Streaming Platforms

Figure 6: Estimation of the total infrastructure costs 5. DISCUSSIONS Related Works. To the best of our knowledge, no pre- vious work can be directly related to ours. Most studies related to live streaming platforms have dealt with Peer-to- Peer (P2P) delivery (or peer-assisted), for which both the transcoding and the delivery is under the responsibility of every broadcaster. Transcoding live stream has also been studied (including works on rate-adaptive technologies [4]) but the object of these works is not related to the manage- ment of many concurrent transcoding process. The third line of research having connection to our paper is the manage- ment of data-centers for massive UGC platforms. However no previous work has considered adaptivity in the treatment of requests, so the trade-off between computing needs and delivery cost has never been studied. Finally, Twitch has been studied in [8], but the focus is on the analysis of the behavior of a small number of professional broadcasters al- though we study it at a macroscopic level with a quantitative approach.
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Infrastructure P2P pour la Réplication et la Réconciliation des Données

Infrastructure P2P pour la Réplication et la Réconciliation des Données

1 Contexte Les systèmes pair-à-pair (P2P) sont en plein essor depuis plusieurs années. Ce paradigme permet de concevoir des systèmes de très grande taille à forte disponibilité et à faible coût sans recourir à des serveurs centraux [VP04]. En effet, les réseaux P2P sont des réseaux overlay (c.-à-.d, des réseaux virtuels construits au dessus des réseaux physiques) [DM03], décentralisés, où tous les nœuds, appelés pairs, jouent à la fois le rôle de serveur et de client. L’organisation dans un tel réseau repose sur l’ensemble des pairs : idéalement, il n’y a aucune entité chargée d’administrer le réseau. Par conséquent, les réseaux P2P garantissent le passage à l’échelle. Il y a trois grandes classes des réseaux P2P [MPV06, HSG08] : les réseaux non-structurés, les réseaux structurés et les réseaux super-pairs. Dans les réseaux non-structurés chaque pair est complètement autonome et la propagation des requêtes se fait généralement par inondation. Les mécanismes sont simples et flexibles mais posent des problèmes importants de performances et de passage à l’échelle. Les réseaux structurés organisent les pairs, ainsi que la répartition des objets sur les pairs, selon une structure stricte et efficace, notamment des tables de hachage distribuées (Distributed Hash Tables ou DHT) [SMKK + 01]. Ces réseaux gagnent à la fois en efficacité et donnent des garanties de recherche. Le prix à payer est la perte d’autonomie de placement des données et le coût de maintenance élevé. Les réseaux super-pairs sont des réseaux hybrides entre les réseaux non structurés et le client-serveur. Comme le réseau client-serveur, certains pairs, appelés super-pairs, jouent le rôle de serveur pour un ensemble de pairs et effectuent des fonctions complexes comme le traitement des requêtes, le contrôle d’accès et la gestion des méta-données. Dans ce type de réseau, les super-pairs sont organisés en mode P2P, choisis automatiquement en fonction de leurs caractéristiques (bande passante, vitesse de traitement, capacité mémoire, etc.) et remplacés en cas de présence d’une panne.
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Supra-extensibilité des réseaux P2P

Supra-extensibilité des réseaux P2P

Une version ´etendue de cet article sera publi´ee dans Infocom 2013 [1]. Keywords: P2P, g´eom´etrie stochastique, analyse de performances 1 Contexte et mod `ele Le sc´enario ´etudi´e est inspir´e du protocole d’´echange de fichiers BitTorrent [5], o`u un fichier est segment´e en petits morceaux ´echang´es entre eux par des pairs leechers au sein d’un r´eseau logique. Quand un leecher a fini son t´el´echargement, il peut rester et continuer `a contribuer au syst`eme. Il est alors seeder.

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Estampillage et Journalisation P2P pour XWiki

Estampillage et Journalisation P2P pour XWiki

Une classe d’application importante dans les systèmes P2P concerne les applications collaboratives où un grand nombre d’utilisateurs doivent pouvoir travailler sur les mêmes données (documents, fichiers, etc.) en parallèle depuis leurs postes de travail. Un exemple de telle application est XWiki [1] [2], un wiki de seconde génération capable de gérer des données structurées et des données non structurées. Un wiki est un outil d'édition de documents en ligne dans lequel les utilisateurs peuvent facilement tisser des liens entre les documents. Il permet la création et la modification de documents à travers une interface Web. Lors de la navigation dans le contenu d'un wiki, un utilisateur peut à tout moment entrer en mode édition pour modifier le contenu de la page. Lorsqu’il a terminé, il peut sauvegarder le nouveau contenu qui vient alors remplacer l'ancienne valeur de la page.
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Systematic Cooperation in P2P Grids

Systematic Cooperation in P2P Grids

3.3 Grid Nodes Virtualization We now explain how Grid nodes of our proposed P2P Grid architecture are vir- tualized. Simulated Grid nodes are instantiated during the initialization of our proposed Grid simulator (see Figure 3.1). The code of these simulated Grid nodes is loaded (using the Java VM class loader) and shared among all instances, but each simulated Grid node has its own separate data structures (those of Peers grow over time due to the storage of metadata about interactions with other Peers). The code of the simulator implementation of Grid nodes is identical to the code of the the middleware implementation. However, some parts of the code have two distinct implementations: One is activated in the simulator, the other one is ac- tivated in live Grid nodes. The dual-implemented Java classes are those involved in communications between Grid nodes, multithreading activities and Task exe- cution. The simulated Grid nodes have to be virtualized, i.e. isolated from their environment. They should have no awareness of the fact that they are being run within the same thread of the same Java VM and interact with a fully controlled, virtualized environment. This corresponds to the virtualization of the Fabric, Con- nectivity and Resource layers [150] in Foster et al.’s Grid architecture.
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VERS UN SYSTEME DE RECOMMANDATION P2P

VERS UN SYSTEME DE RECOMMANDATION P2P

Beaucoup de travaux se font dans ce sens mais le problème principale et qu’il n’existe pas jusqu'à maintenant une plate forme de simulation qui peut permettre d’évaluer ses systèmes vue la difficulté de concevoir des systèmes réel et dynamique tél que le paradigme P2P. L’objectif de notre travail est d’implémenté un réseau peer to peer dans le but d’alléger la tâche des ultrapairs. Dans ces travaux, nous avions tenu compte de l’aspect utilisateur. Autrement dit nous composions les vues des pairs (la couche basse du système) selon les requêtes échangées. Comme suite de ces travaux, nous proposons d’appliquer cette méthode sur la couche maitresse du système, cette fois-ci nous tenons compte de l’aspect structurelle, c'est-à-dire les vues des ultrapairs sont composées à partir des documents réellement dans le system.
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Towards streaming gesture recognition

Towards streaming gesture recognition

The second chapter provides an introduction to one of the most common methods employs in gesture recognition systems, DTW, and the LCSS problem which our method is[r]

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Oscillating acoustic streaming jet

Oscillating acoustic streaming jet

In contrast, such behavior has already been seen for other kinds of jets as confined jets or plume flows. For instance, the mechanism which causes the transition to turbu- lence for a natural convection plume flow was studied by Kimura and Bejan. 15 Likewise, Maurel et al. 16 have recently performed an experimental study of self-sustained oscilla- tions in a confined jet. A specificity of Eckart acoustic streaming is that a controlled external volumetric force is applied within a given fluid volume at any time. Therefore, our contention is that studies carried out in the acoustic streaming configuration can shed new light on this intricate stability problem. The present paper provides thus the first experimental observation of an oscillating acoustic stream- ing jet. As the observed oscillations amplify and exhibit non- linear behavior leading to a disordered state, the present study may also be the first step on the transition to turbulence in acoustic streaming jet.
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Live Fast, Die Young

Live Fast, Die Young

More precisely, in a model with rational and irrational agents, we show that there are situations where irrational agents might rationally stay irrational in the sense that their ex-ante[r]

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VisUML: Live & Interactive Diagrams

VisUML: Live & Interactive Diagrams

Nous voulons montrer que des diagrammes dynamiques, dont le contenu est modi�é et adapté en temps réel à chaque action sur l’IDE du développeur, peuvent être utiles. En e�et, leurs contenus sont adaptés à la tâche active du développeur. Avec nos live diagrammes, nous fournissons une façon e�cace de naviguer entre le code et les di�érentes représentations graphiques.

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