WUW (What Users Want): A Service to Enhance Users' Satisfaction in Content-Based Peer-to-Peer Networks

20 pagesPeer-to-Peer (P2P) architectures are more and more used in Content Delivery Net- works (CDN), because the traditional client-server architectures are burdened by high distribution and maintenance cost, whereas in P2P systems those costs are almost negli- gible. In general, such applications do not take into account user preferences, other than QoS-related parameters. As users resources are the richness of P2P systems, we think it is important to satisfy their preferences concerning the usage of their resources. In this work we propose WUW (What Users Want), a service to improve users' satisfaction in a personal way. WUW runs on top of unstructured P2P systems, and its main goal is to allow users to strategically impact their local neighborhoods according to their own personal preferences. We present first results of experiments, deployed in a cluster, obtained with the prototype implementation of our service, which runs on top of Bit- Torrent, the most used file sharing protocol. We show that BitTorrent performances are not affected by the users strategic choices introduced by WUW. The advantage of our approach is that, without loosing performance, users can chose the peers they want to collaborate with according to their personal preferences

Emergent Overlays for Adaptive MANET Broadcast

Mobile Ad-Hoc Networks (MANETs) allow distributed applications where no fixed network infrastructure is available. MANETs use wireless communication subject to faults and uncertainty, and must support efficient broadcast. Controlled flooding is suitable for highly-dynamic networks, while overlay-based broadcast is suitable for dense and more static ones. Density and mobility vary significantly over a MANET deployment area. We present the design and implementation of emergent overlays for efficient and reliable broadcast in heterogeneous MANETs. This adaptation technique allows nodes to automatically switch from controlled flooding to the use of an overlay. Interoperability protocols support the integration of both protocols in a single heterogeneous system. Coordinated adaptation policies allow regions of nodes to autonomously and collectively emerge and dissolve overlays. Our simulation of the full network stack of 600 mobile nodes shows that emergent overlays reduce energy consumption, and improve reliability and coverage compared to single protocols and to two previously-proposed adaptation techniques

Auditoría de privacidad en PriServ

Cada día aumenta la cantidad de información que se comparte por diferentes sis­temas de cómputo. En este contexto, la compartición de datos en los sistemas par a par (P2P acrónimo en inglés de Peer-to-Peer) puede divulgar datos privados, porque cada par (nodo) puede acceder a los datos del sistema y utilizarlos para diferentes propósitos. Para preservar la privacidad de los datos en estos sistemas, no basta con permitir que el propietario de datos especifique sus políticas de privacidad, sino también hay que proveerlos con herramientas de auditoría para verificar el cumplimiento de dichas políticas. En el presente trabajo de investigación se desarrolló un servicio de auditoría de privacidad para sistemas P2P, el cual verifica el cumplimiento de las políticas de privacidad que PriServ (servicio de privacidad para sistemas P2P) asocia a los datos. Para realizar el servicio de auditoría, en primer lugar, se identificaron las acciones que violan las políticas de privacidad, posteriormente se realizó el diseño de un algoritmo de auditoría y del componente Audit Manager que ejecuta el algoritmo propuesto, finalmente se desarrolló un prototipo que emula un sistema P2P y se realizó la evaluación del algoritmo de auditoría mediante un caso de prueba. Al observar los resultados de evaluar el tiempo que requiere la auditoría, se observó que estos son consistentes con el análisis del orden del algoritmo

Towards improving user satisfaction in decentralized P2P networks

International audiencePeer-to-Peer (P2P) architectures are more and more used in recent content distribution platforms because of their valuable characteristics as scalability, performance, and negligible maintenance and distribution costs. In general, P2P applications allow users to provide preferences that are mainly related to performance, like number of connections and bandwidth limits. As user resources are the wealth of P2P systems, we think it is important to satisfy user preferences in a more meaningful and personalized way. Users should be able to define the kind and quality of peers they prefer to exchange with. In this work, we present What Users Want (WUW), a framework to measure and improve the satisfaction of the users based on personal preferences that reflect their expectations from the P2P system. We then present the design of a distributed P2P service that implements our framework. Experimental results, obtained with a prototype running on top of BitTorrent, show improvement of user satisfaction and the possibility to minimize the impact on the overall performance of the content distribution

Construction auto-organisante de tables de hachages réparties et évaluation en conditions réelles

Les principes d'auto-organisation sont adaptés aux systèmes repartis à grande échelle dans des environnements dynamiques. En utilisant des actions simples, non coordonnées et fondées seulement sur une connaissance locale du système, un ensemble de pairs peut converger de façon autonome vers un état global, comme une structure de réseau logique particulière. Dans cet article, nous proposons d'étudier et d'évaluer l'utilisation de ce type de construction ap-pliquée à des structures de tables de hachage réparties (THR) et de les étudier en conditions pratiques. Plus spécifiquement, nous considérons l'utilisation de protocoles épidémiques (gossip) pour l'amorçage et le maintien de plusieurs structures de THR. Nous utilisons comme base le protocole T-Chord, qui utilise le cadre de conception de systèmes auto-organisants T-Man. Nous étendons ces travaux à la construction de deux THRs supplémentaires, T-Pastry et T-Kademlia. Contrairement aux travaux précédemment publiés sur ce sujet, nous fondons notre évaluation sur un déploiement d'un prototype sur un cluster formé de 600 pairs. Nos résultats montrent que, tout en atteignant de façon systématique la structure idéale de la THR considé-rée, les mises en oeuvre auto-organisantes tolèrent un dynamisme plus grand (va-et-vient) des pairs de la THR, et montrent que les solutions fondées sur les protocoles épidémiques ont un intérêt concret pour un déploiement en conditions réelles

On the Impact of Indirect WAN Routing on Geo-Replicated Storage

International audience—Micro-clouds infrastructures allow supporting applications on local and energy-efficient resources. Communication between micro-clouds takes place on shared and non-dedicated Internet links. Network control and optimization can only happen at the edge. For availability and persistence, the storage of application data must be geo-replicated. Maintaining strong data consistency under concurrent accesses requires delay-sensitive coherence protocols, linking the performance of the storage to that of the network linking micro-clouds. We evaluate if the use of network control at the edge of a European-wide multi-site testbed, together with appropriate network monitoring , can allow improving the performance of ZooKeeper, a strongly-consistent replicated store. Our approach leverages the indirect routing of coherence protocol traffic in the presence of network triangle equality violations. We analyze the impact on storage of variations in WAN performance, and show how the use of traffic redirection can help reducing it

Evaluating the Cost and Robustness of Self-organizing Distributed Hash Tables

Self-organizing construction principles are a natural fit for large-scale distributed system in unpredictable deployment environments. These principles allow a system to systematically converge to a global state by means of simple, uncoordinated actions by individual peers. Indexing services based on the distributed hash table (DHT) abstraction have been established as a solid foundation for large-scale distributed applications. For most DHTs, the creation and maintenance of the overlay structure relies on the exploration and update of an already stabilized structure. We evaluate in this paper the practical interest of self-organizing principles, and in particular gossip-based overlay construction protocols, to bootstrap and maintain various DHT implementations. Based on the seminal work on T-Chord, a self-organizing version of Chord using the T-Man overlay construction service, we contribute three additional self-organizing DHTs: T-Pastry, T-Kademlia and T-Kelips. We conduct an experimental evaluation of the cost and performance of each of these designs using a prototype implementation. Our conclusion is that, while providing equivalent performance in a stabilized system, self-organizing DHTs are able to sustain and recover from higher level of churn than their explicitly-created counterparts, and should therefore be considered as a method of choice for deploying robust indexing layers in adverse environments

Towards a Hybrid Client/Server and P2P Architecture for Content Delivery over the Internet

International audienc

Reactive Overlays for Adaptive Routing in Mobile Ad hoc Networks

Several emerging applications for the Internet of Things, vehicular networks, or decentralized communication using smartphones rely on Mobile Ad hoc Networks (MANETs). These networks are temporary deployments of nodes equipped with infrastructure-less wireless communication. MANETs operate in highly dynamic conditions where nodes move at will, interferences are a constant and density is heterogeneous. Routing is a fundamental operations in MANETs. Our evaluation of existing routing protocol for MANETs shows that, while proactive routing protocols are suitable for highly dynamic networks, reactive routing protocols perform best in dense and more static scenarios. No protocol alone can systematically perform well when density is heterogeneous. We propose RoVy, a self-aware adaptive approach for routing in heterogeneous MANETs. Based on independent estimations of density and mobility, RoVy allows nodes to automatically switch between AODV, a reactive routing protocol and DSDV, a proactive protocol. Interoperability protocols support the integration of AODV and DSDV in a single heterogeneous MANET. RoVy maintains a dissemination overlay to speed-up route discovery and improves the emergence of alternative routes to destination nodes. Our simulations of the full network stack with 1,000 nodes shows that RoVy outperforms singular routing protocols in terms of performance, costs and reliability

Emergent Overlays for Adaptive MANET Broadcast

Mobile Ad-Hoc Networks (MANETs) allow distributed applications where no fixed network infrastructure is available. MANETs use wireless communication subject to faults and uncertainty, and must support efficient broadcast. Controlled flooding is suitable for highly-dynamic networks, while overlay-based broadcast is suitable for dense and more static ones. Density and mobility vary significantly over a MANET deployment area. We present the design and implementation of emergent overlays for efficient and reliable broadcast in heterogeneous MANETs. This adaptation technique allows nodes to automatically switch from controlled flooding to the use of an overlay. Interoperability protocols support the integration of both protocols in a single heterogeneous system. Coordinated adaptation policies allow regions of nodes to autonomously and collectively emerge and dissolve overlays. Our simulation of the full network stack of 600 mobile nodes shows that emergent overlays reduce energy consumption, and improve reliability and coverage compared to single protocols and to two previously-proposed adaptation techniques