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Tesi sul tema "Peer to peer"
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1
Brasini, Nicholas. "Confronto tra meccanismi di anonimizzazione per il cloud peer-to-peer". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19422/.
Testo completoAbstract (sommario):
Lo scopo principale di questa tesi è quello di implementare la rete di anonimizzazione Invisible Internet Project (I2P) all'interno di un prototipo esistente basato su un'architettura cloud peer-to-peer (P2P). Tale prototipo implementa al proprio interno la rete di anonimizzazione The Onion Router (Tor) e il secondo obiettivo di questa tesi è quello di analizzare e valutare le performance offerte da queste due tipologie di reti. Il prototipo, basandosi su un sistema decentralizzato P2P che, rispetto a quello centralizzato non ha il problema di rappresentare un single point of failure, permette la scoperta di peer all'interno della rete mediante algoritmi di gossip, abili a riconoscere i churn, ovvero quei nodi appartenenti alla rete che si sono disconnessi non facendone più parte. In questo modo ogni peer sarà aggiornato sullo stato dei peer conosciuti e riuscirà ad eliminare dal proprio elenco i peer disconnessi dalla rete evitando di contattarli inutilmente. Oltre alla funzionalità di ricerca di altri peer all'interno della rete, il prototipo mette a disposizione algoritmi e script utili per poter monitorare la rete stessa ed il suo comportamento e per poter costruire overlay tra alcuni dei peer appartenenti alla rete.
2
Liu, Nianwang, e 刘年旺. "Request peer selection for peer-to-peer streaming". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206752.
Testo completoAbstract (sommario):
As the Internet develops and technology evolves, multimedia traffic dominates the Internet. Traditional client-server based video streaming solutions are expensive and suffering from the scalability issue. Inspired by the immense success and efficiency of BitTorrent in distributing file contents to large groups of users, the peer-to-peer (P2P) paradigm has been adopted to provide streaming services including both P2P video-on-demand (VoD) and P2P live streaming.
Among the design challenges, one open yet fundamental question is, how to identify the most suitable neighbor for a peer to make a piece request. We refer this problem as the request peer selection problem. Properly allocating the piece request to potential providers is essential to the system and would help to balance the load at each peer. A well designed request peer selection algorithm increases the requestor’s probability to download the desired piece timely which leads to enhanced video quality and improved playback continuity. This thesis aims to enhance the overall system performance by proposing optimized request peer selection algorithms for both P2P VoD and P2P live streaming systems.
In P2P VoD, participating peers start playback from the very beginning of a stored video. The playback-points of peers, as well as the amount of video contents/pieces the peers cached, depend on when they join the video session, or their viewing ages. The content buffered by younger peers is a subset of older peers, thus collaborative piece exchange among peers is undermined due to the unbalanced supply and demand. To address this issue, a playback-point based request peer selection algorithm: closest playback-point first (CPF) is proposed. Specifically, when a peer requests a particular video piece, among the set of potential providers, a request is sent to the peer that has the smallest playback-point difference with itself. With CPF, peers with similar content availability are loosely grouped into clusters to maximize the utilization of individual peer’s upload capacity. Extensive packet level simulations show that with CPF, the video playback quality is enhanced and the VoD server load is significantly reduced.
Unlike P2P VoD, P2P live streaming systems have to meet real-time playback constraints, which makes it even more challenging. To better regulate the network traffic and to balance the load among peers, a service response time (SRT) based request peer selection algorithm is proposed. In particular, a peer in the network estimates the service response time (SRT) between itself and each neighboring peer. SRT is measured from when a data piece request is sent until the requested piece arrives. When a peer makes a piece request, the neighbor with smaller SRT and fewer data pieces would be favored. The rationale is: smaller SRT implies excess serving capacity and fewer data pieces suggests fewer potential piece requests received. Extensive packet level simulations show that the traffic load in the network is better balanced, the streaming server load is reduced, and the overall quality of service, measured by playback continuity, startup delay etc., is improved.published_or_final_version
Electrical and Electronic Engineering
Master
Master of Philosophy
3
Schreiber, Daniel. "Peer-To-Peer-Videostreaming". Master's thesis, Universitätsbibliothek Chemnitz, 2005. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200501398.
Testo completoAbstract (sommario):
Für Übertragung von Live-Videodaten an mehrere
Empfänger gibt es als etablierte Technologien die
Übertragung per Multicast an mehrere Empfänger
sowie die Unicast-Übertragung an jeden Empfänger
von einem Verteilpunkt aus. Nachteilig ist im
ersten Fall, dass viele ISPs kein Multicast
unterstützen, im zweiten Fall der hohe
Bandbreitenbedarf am Verteilpunkt. Die
Unterschiede in der verfügbaren Bandbreite von
ISP-Zugängen (DSL, ISDN) und Campusnetzwerken
(z.B. Studentennetzen) erfordern es, das
Videomaterial in mehreren Qualitätsstufen
anzubieten.
Im Team wurde ein System entworfen und realisiert,
das aus einer Quelle effizient verschiedene
Qualitätsstufen des Videomaterials erzeugt
("Videoteil") und dieses mittels
Peer-To-Peer-Technologie verteilt ("Netzwerkteil").
Diese Arbeit enthält den den Netzwerkteil.
4
Magnani, Marco. "Progettazione e implementazione di un protocollo Peer-to-Peer per il sensing partecipativo". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amslaurea.unibo.it/2686/.
Testo completo
5
Ehrig, Matthias. "Workshop Peer-to-Peer-Computing". Universitätsbibliothek Chemnitz, 2002. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200201175.
Testo completoAbstract (sommario):
Gemeinsamer Workshop von Universitaetsrechenzentrum und Professur Rechnernetze und verteilte Systeme der Fakultaet fuer Informatik der TU Chemnitz.
Vortraege zu verschiedenen Themen der Entwicklung der Informatik und zu Technologien im Rechenzentrum einer Universitaet
6
Babbar, Abhimanyu. "Peer to Peer Search Protocol". Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-186713.
Testo completoAbstract (sommario):
Decentralized full-text search is still an unsolved problem in peer-to-peer research. As part of this thesis, we introduce Sweep, a fully decentralized full-text search engine built on Apache Lucene, that takes significant steps towards providing reliable, low-latency, and accurate search results. Our main contributions include a novel gossip-based protocol for fast and efficient replication of the search index and a protocol for the automated sharding of the search index. Therefore, each peer maintains a replica of a bounded-size subset of the whole search index also known as shard. Our approach is based on a low overhead gossip-based leader selection algorithm within each shard, whose cost is independent of the number of peers. For each shard, peers add new index entries to the leader group, and peers securely pull updates within their shard using a Gradient topology that ensures efficient dissemination of updates in log(N) hops within the shard. The full-text search involves a fanout search to each shard, with latency variance reduction techniques to help achieve low response times. We show in simulation the viability of our approach and its robustness to failures and flash crowds.
7
Waller, Michael, e Emelie Salleke. "Peer-to-peer som företagslösning". Thesis, Blekinge Tekniska Högskola, Institutionen för programvaruteknik och datavetenskap, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2378.
Testo completoAbstract (sommario):
Problemområde: Idag är användandet av peer-to-peer (P2P) - applikationer såsom KaZaa, ICQ och Seti@home utbrett bland privatpersoner. Användningen inom företag är dock ännu i sin linda. Vi kommer därför i den här uppsatsen utreda om ett eventuellt införande av P2P- teknik i ett företagsnätverk ger några fördelar jämfört med en klassisk Client/Server-lösning. Hypotes: Arbetet bygger på hypotesen: ?En P2P-lösning ger fördelar för företaget jämfört med en Client/Server-lösning? Genomförande: För jämförelsen mellan P2P och Client/Server definierades och jämfördes fem områden: Säkerhet, Användbarhet, Tillgänglighet, Bandbredd samt Utrustningskrav. Slutsats: Inom områdena Användbarhet och Tillgänglighet ger en P2P-lösning klara fördelar, däremot inom områdena Säkerhet och Bandbredd visar Client/Server- lösningen istället klara fördelar. Området Utrustningskrav är oavgjort då det inte finns någon märkbar skillnad på lösningarna. Säkerhetsproblemen är P2P-teknologins akilleshäl och det problem som är mest troligt att stoppa stora investeringar i framtiden om det inte löses. Slutsatsen av vår jämförelse blir sålunda: För ett företag som redan har ett existerande Client/Server-nätverk är det inte någon idé att helt byta system, däremot kan det vara av intresse att introducera en applikation som möjliggör skapandet av så kallade Virtuella Nätverk. För ett helt nytt företag kan skapandet av ett P2P-nätverk vara ett väl så intressant alternativ till Client/Server. Detta förutsätter dock att säkerheten inte är så viktig för företaget eller att säkerhetsproblemen lösts.
8
Hu, Tim Hsin-ting Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Restructuring peer-to-peer networks". Awarded by:University of New South Wales. School of Electrical Engineering and Telecommunications, 2006. http://handle.unsw.edu.au/1959.4/25171.
Testo completoAbstract (sommario):
The popularity of peer-to-peer networks has grown tremendously in recent times as a result of the ever-improving capabilities of host entities at the edge and the ubiquitous reach of the Internet. The growth has fueled the realization of many peer-to-peer networks in both academia and the commercial arena. Peer-to-peer networks generally fall into one of these categories ??? centralized systems with server-like entities in the network; unstructured systems with random topology and message routing, and structured systems with deterministic topology and routing behavior. Surveying the major peer-to-peer networks in each category, one can conclude that the each of the categories exhibit very different characteristics and properties from one another. This thesis addresses the problems in the peer-to-peer networking space by employing two overarching principles. Firstly, desirable properties of systems in one category can be adopted by another to achieve restructuring. In short, restructuring involves the injection of structure into unstructured networks and conversely loosening the rigidity in structured systems. Secondly, as much as possible, participating peers in the network are designed to be homogeneous in functionality recognizing that they are heterogeneous in capabilities. True to the concept of the peer-to-peer paradigm, this principle keeps participants functioning as fellow peers rather than imposing hierarchical differences in the roles within the network. We describe three contexts in which the issues pertaining to the peer-to-peer networks in view can be addressed by applying the principle of restructuring. For the Mobile Agent Peer-to-Peer architecture, we adopt centralized concepts into the unstructured peer-to-peer network while maintaining homogeneity in functionality through the use of mobile agents. The architecture shields excessive traffic from peers with limited resources and allows more capable peers to share others??? burden. Through the use of mobile agents, logical hierarchy is avoided and thus the second overarching principle of homogeneity is preserved. For Gnutella Clusters, concepts from the structured systems are adopted to facilitate the formation and maintenance of clustering in unstructured networks. Clustering limits the amount of flooding in the network and thus conserves bandwith. The clustering algorithm is decentralized to all peers, and does not need a set of participants to have special functionality ??? thus preserving the generic nature of all peers. In Autonomic Decentralized Service Directory platform, structure is released from the underlying Chord network to provide better support for service registration and searching. The strict requirements for deterministic routing and lookup which characterize structured systems are granted some leniency for the ability to avoid misbehaving nodes and provide incentives for peers to behave properly.
9
Blomqvist, Ulf. "Mediated peer (to peer) learning". Licentiate thesis, Stockholm, 2006. http://www.diva-portal.org/kth/theses/abstract.xsql?dbid=3989.
Testo completo
10
BRACCIALE, LORENZO. "Peer-to-peer multimedia communication". Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/1308.
Testo completoAbstract (sommario):
I sistemi Peer-to-Peer (P2P) sono stati inventi, messi in campo e studiati da più di
dieci anni, andando al di là della semplice applicazione per scambio di file. Nelle reti P2P i partecipanti
si organizzano in una rete "overlay" che è astratta rispetto alle caratteristiche della sottostante rete fisica.
Scopo di questi sistemi è la distribuzione di risorse quali contenuti, spazio di memorizzazione o cicli macchina. Gli utenti quindi giocano un ruolo attivo e possono essere considerati come sia clienti che serventi allo stesso tempo per il particolare servizio che la rete P2P offre.
Lo scopo di questa tesi di dottorato è lo studio di questi sistemi ed il dare un contributo nella loro analisi
prestazionale. L'analisi mira a valutare le prestazioni raggiunte dai sistemi e/o i limiti teorici raggiungibili.
Infatti, nonostante esistano diversi meccanismi per il peer-to-peer streaming, l'analisi prestazionale di questo tipo di sistemi può essere considerata ancora nella sua infanzia. A questo scopo, i contributi principali di questa tesi di dottorato sono: i)la derivazione di un limite teorico per il ritardo nei sistemi di
P2P streaming, ii) la creazione di un algoritmo che sfrutti le conoscenze acquisite attraverso il lavoro teorico, iii) l'analisi prestazionale dell'algoritmo utilizzando un simulatore espressamente progettato per riprodurre le caratteristiche delle reti P2P reali composte da centinaia di migliaia di nodi che si connettono e disconnettono in continuazione.Peer-to-Peer (P2P) systems have been invented, deployed and researched for more than ten years and went far beyond the simple file sharing applications. In P2P networks, participants organize themselves in an overlay network that abstracts from the topological characteristics of the underlying physical network. Aim of these systems is the distribution of some kind of resources like contents, storage, or CPU cycles. Users, therefore, play an active role so that they can be considered as client and server at the same time, for the particular service that is provided through the P2P paradigm. Goal of this dissertation thesis is to study these systems, and give contributes in their performance evaluation. The analysis will aim to evaluate the achieved performance of a system and/or the performance bounds that could be achievable. In fact, even if there are several proposals of different systems, peer-to-peer streaming performance analysis can be considered still in its infancy and there is still a lot of work to do. To this aim, the main contributes of this dissertation thesis are i) the derivation of a theoretical delay bounds for P2P streaming system ii) II the creation of an algorithm that exploits the new insights that come out from the theoretical study iii) the performance evaluation of this algorithm using an ad-hoc simulator, expressly tailored to reproduce the characteristics of the real-world P2P streaming systems, composed by hundred thousands of intermittently connected users.
11
Åslund, Jonas. "Authentication in peer-to-peer systems". Thesis, Linköping University, Department of Electrical Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1222.
Testo completoAbstract (sommario):
In the environment of the 3:rd generation Internet based on peer-to-peer architecture, well-trusted methods must exist to establish a secure environment. One main issue is the possibility to verify that a node actually is who it claims to be (authentication). Establishment of authentication between nodes in a peer-to-peer environment where nodes are exchanging information directly with each other requires more planning than in a typical client-server environment where the authentication methods are server-based. The peer-to-peer applications described in this report use authentication methods based on central authorities as well as solutions without central authorities.
Lack of standards in the way peer-to-peer systems should communicate and apply security lead to a variety of “local” communication and security solutions. These local solutions make different applications incompatible with each other, meaning that a peer using one application will not be able to communicate and exchange information with other peers using some other application.
12
Fischbach, Kai. "Strukturbildung in Peer-to-peer-Netzwerken". Köln Kölner Wiss.-Verl, 2006. http://d-nb.info/988331624/04.
Testo completo
13
Fischbach, Kai. "Strukturbildung in Peer-to-Peer-Netzwerken /". Köln : Kölner Wiss.-Verl, 2008. http://d-nb.info/988331624/04.
Testo completo
14
Leslie, Matthew John. "Reliable peer to peer grid middleware". Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:90d21e54-3849-46d1-aa8a-5f0c4f80d42a.
Testo completoAbstract (sommario):
Grid computing systems are suffering from reliability and scalability problems caused by their reliance on centralised middleware. In this thesis, we argue that peer to peer middleware could help alleviate these problems. We show that peer to peer techniques can be used to provide reliable storage systems, which can be used as the basis for peer to peer grid middleware. We examine and develop new methods of providing reliable peer to peer storage, giving a new algorithm for this purpose, and assessing its performance through a combination of analysis and simulation. We then give an architecture for a peer to peer grid information system based on this work. Performance evaluation of this information system shows that it improves scalability when compared to the original centralised system, and that it withstands the failure of participant nodes without a significant reduction in quality of service. New contributions include dynamic replication, a new method for maintaining reliable storage in a Distributed Hash Table, which we show allows for the creation of more reliable, higher performance systems with lower bandwidth usage than current techniques. A new analysis of the reliability of distributed storage systems is also presented, which shows for the first time that replica placement has a significant effect on reliability. A simulation of the performance of distributed storage systems provides for the first time a quantitative performance comparison between different placement patterns. Finally, we show how these reliable storage techniques can be applied to grid computing systems, giving a new architecture for a peer to peer grid information service for the SAM-Grid system. We present a thorough performance evaluation of a prototype implementation of this architecture. Many of these contributions have been published at peer reviewed conferences.
15
Zoupanos, Spyros. "Efficient peer-to-peer data management". Paris 11, 2009. http://www.theses.fr/2009PA112298.
Testo completoAbstract (sommario):
Le développement de l'internet a conduit à une grande augmentation de l'information disponible pour les utilisateurs. Ces utilisateurs veulent exprimer leur besoins de manière simple, par l’intermédiaire des requêtes, et ils veulent que ces requêtes soient évaluées sans se soucier où les données sont placées ou comment les requêtes sont évaluées. Le travail qui est présenté dans cette thèse contribue à l'objectif de la gestion du contenu du Web de manière déclarative et efficace et il est composé de deux parties. Dans le premier partie, nous présentons OptimAX, un optimiseur pour la langage Active XML qui est capable de reécrire un document Active XML donné dans un autre document équivalent dont l'évaluation sera plus efficace. OptimAX contribue à résoudre le problème d'optimisation des requêtes distribuées dans le cadre d'Active XML et nous présentons deux études de cas. Dans le deuxième partie, nous proposons une solution au problème de l'optimisation d'un point de vue différent. Nous optimisons des requêtes en utilisant un ensemble des requêtes pré-calculées (vues matérialisées). Nous avons développé une plateforme pair-à-pair, qui s'appelle ViP2P (views in peer-to-peer) qui permet aux utilisateurs de publier des documents XML et de spécifier des vues sur ces documents en utilisant une langage de motifs d'arbres. Quand un utilisateur pose une requête, le système essaiera de trouver des vues qui peuvent être combinées pour construire une réécriture équivalente à la requête. Nous avons fait des expérimentations en utilisant des ordinateurs des différents laboratoires en France et nous avons montré que notre plateforme passe à l'échelle jusqu'à plusieurs GB de donnéesInternet has led to a fundamental increase of information that is available to its users over the latest years. The users want to express their needs by simple means, such as queries and they want their queries to be evaluated without caring where the data are placed or how the queries are optimized. The work presented in this thesis contributes to the goal of declarative and efficient management of Web content in distributed settings and it is divided into two main chapters. In the first chapter we study OptimAX, an optimizer for the Active XML language which is able to rewrite a given Active XML document to an equivalent document which would, very likely, have smaller execution cost. With OptimAX we focus on the problem of distributed query optimization in the Active XML setting and we present two interesting case studies inspired by the R\&D projects in which our group has been involved. In the second chapter, we propose solutions to the optimization problem from a different perspective. We optimize queries using a set of precomputed queries (materialized views). We have developed a peer-to-peer platform, called ViP2P (views in peer-to-peer) that gives to the users the opportunity to publish their XML documents and to specify views over these documents using a tree pattern language. Whenever a user asks a query, the system will try to find views that can be combined in order to find a rewriting equivalent to the asked query. We have carried WAN experiments that show the scalability of the ViP2P platform
16
Eriksson, Felix. "Enabling Peer-to-Peer Co-Simulation". Thesis, Högskolan i Halmstad, Akademin för informationsteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-29553.
Testo completoAbstract (sommario):
Simulation enables preliminary testing of products that may otherwise be dicult, ex-pensive, or dangerous to test physically. Unfortunately, intellectual property concernscan make it dicult or impossible to share the human-readable simulation models toend-users. In fact, there can even be diculties with sharing executables because ofthe possibility for reverse-engineering. This presents a problem when simulating if themodel relies on components for which the source code or executable is not available,such as proprietary components developed by another party. This thesis investigateswhether it is possible to enable a set of networked peers to all take part in computingthe same simulation without any of them having access to the entire model. One way tosolve this problem is to let each system that holds a model of a component to computeits part of the simulation for a single timestep and to share the new state through peer-to-peer connections with the other systems, once a response has been received fromall other peers, the local simulation can advance one timestep and the process can berepeated. But running a simulation over a network can make it signicantly slower,since local operations on the CPU and memory are much faster than operations overa network, and the peers will be spending most of their time waiting for each other asa result. To avoid such delays, each peer maintains expected values for variables thatare not in the local model, and updates are sent only when a local variable changes.These updates are stamped with the local simulation-time, thus allowing the recipientpeers to know when the update is required in the simulations future, or to when itshould be retroactively applied in the simulations past. Using this technique, the peerscan compute their respective local models under the assumption that the variablesthat the other peers control are unchanged. Thus the peers can advance any numberof timesteps without needing to stop and wait for other peers. These techniques willlikely result in wasted work if one or more peers are advancing their simulation timeslower than the others, when this happens, the peers have the ability to re-distributethe workload on the y by transferring control over models. This also makes it possibleto accommodate for systems joining or leaving the simulation while it is running.In this thesis we show that co-simulating in this fashion is a workable option to tra-ditional simulation when the local models are incomplete, but that the performanceis very dependent on the models being simulated. Especially the relation between thefrequency of required synchronizations, and the time to compute a timestep. In ourexperiments with fairly basic models, the performance ratio, compared to traditionalsimulation, ranged between less than one percent of that of traditional simulation, upto roughly 70%. But with slower models always having a better ratio.
17
Hill, Celeste. "Cultivating Competence: Peer-to-peer Interviewing". Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/secfr-conf/2019/schedule/15.
Testo completoAbstract (sommario):
The power of peer-to-peer teaching and learning was explored in an interviewing assignment between upper and lower classes in Human Development and Family Life Education. The freshmen and sophomores participated in a Professional Perspectives in Family Science class, whereas the juniors and seniors were completing their practicum experiences. In both classes there is a focus on professionalism and career competence. The two groups of students were pair-matched and the upperclass Practicum students interviewed the underclass Professional Perspectives students as if it were a formal graduate school admission or an employment interview. Both participants had to prepare for the mock interview by partnering with the university career development center. After the interview the upperclass participant of the pair provided feedback to the underclass student. The metacognitive learning in this task was that upperclass students had to reflect on their own performance. By being in the interviewee role, they became aware of the parameters that could be explored in more formal real-life situations, and had an opportunity to enhance their competence for future interviews.
18
Eliáš, Luboš. "Zabezpečený peer to peer komunikační systém". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217284.
Testo completoAbstract (sommario):
The main aim of this master's thesis is to implement a common, secure and peer-to-peer communication system. The system has ability to automatically establish and run a secure end-to-end connection. It has this ability even if a network address translator is in the way to the destination system, without need of any explicit configuration of this translator. The security procedures of this system are in a transparent manner masked from individual applications, which had to solve this challenge in their own way. A responsibility for a security is delegate to an application-independent subsystem working within the core of an operating system. The security of this subsystem is based on capturing the outbound and inbound IP packets and their authentication and encryption. The system was successfully implemented in MS Windows XP operating system, in programming language C++. Transfer rate of communication tunnel in different network bandwidth speeds was measured. Result shows, that in the case of use the system on standard PC sold nowadays is practically no decrease of the transfer rate in comparison to a common channel.
19
Arnedo, Moreno Joan. "Securing group based peer-to-peer systems". Doctoral thesis, Universitat Politècnica de Catalunya, 2009. http://hdl.handle.net/10803/31741.
Testo completoAbstract (sommario):
Peer-to-peer applications enable a group of users to create a communications framework from scratch without the need of a central service provider. This is achievable via the aggregation of resources each one of them provide, creating a completely distributed collaborative environment based in a flat hierarchy of users, without the need for centralization. Usually, peer-to-peer applications are conceptualized as a global network, without any kind of logical segmentation or segregation as far as resource availability is concerned. At every model, any peer may access any resource available within the network just by being able to reach the peer that provides such resource. Although having a unique huge open network may be desirable for some applications, there are cases in which it might be interesting to create different, but not necessarily disjoint, groups of peers operating under the same global peer-topeer network.
In order for peer groups to be able to operate effectively in a global peer-to-peer network, additional security services must be provided. These mechanisms should allow peers to be able to prove group membership to other members of the group, so they can be granted access to group resources, as well as ensuring that resource discovery and message exchange between peer group members remain secure. A group may need to limit membership for various reasons, such as ensuring privacy, anonymity or enforcing that peer group members are up to some specific parameter (data shared, performance, computing power, etc.)
The goals of this PhD. thesis are twofold, the reason being the fact that securing a peer group can be divided at two distinct, but interrelated, layers:
• Enabling effective group membership, starting from the process by which any peer becomes part of a peer group and then, following, the mechanisms by which such peer may prove its membership to other group members for the rest of the membership's lifecycle (peer group access control).
• Providing a secure environment for standard operations within a peer group, which functions once any peer's membership to the group has already been established. Typical operations at this layer are those of resource location and retrieval, or messaging.
In order to achieve the former goal, basic group membership and access control scenarios are categorized and formalized as part of the research work in order to assess which are the current challenges. From this study, we present a generic model proposal that fulfils the objectives of autonomy, keeps a pure peer-to-peer model and the possibility to be used in different peer-to-peer frameworks.
The later goal focuses in secure mechanisms in order to provide basic security services to both resource discovery and message exchange. However, in contrast with group membership models, where a generic approach is feasible, peer group operation security is intimately tied to each specific peer-to-peer framework, since each one specifies resource location and messaging primitives in a different manner. For that reason, a specific one has been chosen for the research work: JXTA. Such election is due to the fact that JXTA's architecture is entirely based on the concept of peer groups, since it was the one to first define the concept of peer group, providing an excellent testbed for peer group research
20
Suárez, Touceda Diego. "Security in peer-to-peer communication systems". Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/110547.
Testo completoAbstract (sommario):
P2PSIP (Peer-to-Peer Session Initiation Protocol) is a protocol developed by the IETF (Internet Engineering Task Force) for the establishment, completion and modi¿cation of communication sessions that emerges as a complement to SIP (Session Initiation Protocol) in environments where the original SIP protocol may fail for technical, ¿nancial, security, or social reasons. In order to do so, P2PSIP systems replace all the architecture of servers of the original SIP systems used for the registration and location of users, by a structured P2P network that distributes these functions among all the user agents that are part of the system. This new architecture, as with any emerging system, presents a completely new security problematic which analysis, subject of this thesis, is of crucial importance for its secure development and future standardization.
Starting with a study of the state of the art in network security and continuing with more speci¿c systems such as SIP and P2P, we identify the most important security services within the architecture of a P2PSIP communication system: access control, bootstrap, routing, storage and communication. Once the security services have been identi¿ed, we conduct an analysis of the attacks that can a¿ect each of them, as well as a study of the existing countermeasures that can be used to prevent or mitigate these attacks. Based on the presented attacks and the weaknesses found in the existing measures to prevent them, we design speci¿c solutions to improve the security of P2PSIP communication systems. To this end, we focus on the service that stands as the cornerstone of P2PSIP communication systems¿ security: access control. Among the new designed solutions stand out: a certi¿cation model based on the segregation of the identity of users and nodes, a model for secure access control for on-the-¿y P2PSIP systems
and an authorization framework for P2PSIP systems built on the recently published Internet Attribute Certi¿cate Pro¿le for Authorization.
Finally, based on the existing measures and the new solutions designed, we de¿ne a set of security recommendations that should be considered for the design, implementation and maintenance of P2PSIP communication systems.
21
Tati, Kiran. "Exploiting heterogeneity in peer-to-peer systems". Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3234984.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--University of California, San Diego, 2006.Title from first page of PDF file (viewed December 7, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 102-108).
22
Ahmetspahic, Emir. "Distributed Computing in Peer-to-peer Networks". Thesis, Linköping University, Department of Computer and Information Science, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2575.
Testo completoAbstract (sommario):
Concepts like peer-to-peer networks and distributed computing are not new. They have been available in different forms for a long time. This thesis examines the possibility of merging these concepts. The assumption is that non-centralized peer-to-peer networks can be used for effective sharing of computing resources. While most peer-to-peer systems today concentrate on sharing of data in various forms, this thesis concentrates on sharing of clock cycles instead of files.
23
Aasen, Frode Voll, e Tom-Christian Bjørlo Johannessen. "Hybrid Peer-to-Peer Solution for MMORPGs". Thesis, Norwegian University of Science and Technology, Department of Telematics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-8976.
Testo completoAbstract (sommario):
This thesis provides an introduction to the MMORPG genre, and the challenges of engineering a networking system supporting these games, as well as the state of the art titles that exist on the market today. Further it describes the design and development of a peer-to-peer networking system to support MMORPG games, and basic testing of this system. It focuses on a broad theoretical approach to provide a solid background to understand the options available and choices made in the design of the system. The thesis presents a hybrid peer-to-peer concept that aims to reduce costs of operating an MMORPG, allowing smaller game developers to compete against major titles. It includes the main features that should be enabled in a distributed MMORPG architecture. The concept is designed to be flexible in terms of further development, allowing new features to be added with ease and providing game designers with multiple options. A proof-of-concept demo is implemented in Java, displaying the features through a simple interface, and tests showed that the concept has potential to challenge the client-server solutions that are dominating the market today.
24
Lennartsson, Petter, e Kristoffer Skogbert. "Peer-to-peer – En teknik för företag?" Thesis, Växjö University, School of Mathematics and Systems Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-435.
Testo completoAbstract (sommario):
Innehåll: Peer-to-peer är idag en teknik som i de flesta fall förknippas med fildelning.
I detta arbete har vi försökt klargöra vilka andra möjligheter tekniken erbjuder för företag och i dessa möjligheter försökt hitta fördelar och nackdelar med tekniken. Klient-server är en vanlig teknik idag bland företag och i arbetet undersöks om peer-to-peer kan vara en möjlig konkurrent till denna teknik.
Syftet med rapporten är att se om det finns intresse bland företagen att använda sig av de möjligheter som peer-to-peer tekniken erbjuder samt att undersöka hur den skulle kunna användas.
Contents: Peer-to-peer is a technique that is most often associated with file sharing. In this thesis we try to examine what other possibilities the technique has to offer to companies, and in these possibilities, determine pros and cons. Client-server is a common technique today, especially amongst companies, and in this thesis we study if peer-to-peer can be a possible competitor to this technique. The purpose with the study is to see if companies are interested in using the possibilities offered in the peer-to-peer technique and how these possibilities could be used in a company.
25
Mohammed, Sirajuddin. "PERFORMANCE EVOLUTION OF PEER TO PEER NETWORKS". Thesis, Högskolan Dalarna, Datateknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:du-3959.
Testo completoAbstract (sommario):
This thesis work concerns about the Performance evolution of peer to peer networks, where we used different distribution technique’s of peer distribution like Weibull, Lognormal and Pareto distribution process. Then we used a network simulator to evaluate the performance of these three distribution techniques.During the last decade the Internet has expanded into a world-wide network connecting millions of hosts and users and providing services for everyone. Many emerging applications are bandwidth-intensive in their nature; the size of downloaded files including music and videos can be huge, from ten megabits to many gigabits. The efficient use of network resources is thus crucial for the survivability of the Internet. Traffic engineering (TE) covers a range of mechanisms for optimizing operational networks from the traffic perspective. The time scale in traffic engineering varies from the short-term network control to network planning over a longer time period.Here in this thesis work we considered the peer distribution technique in-order to minimise the peer arrival and service process with three different techniques, where we calculated the congestion parameters like blocking time for each peer before entering into the service process, waiting time for a peers while the other peer has been served in the service block and the delay time for each peer. Then calculated the average of each process and graphs have been plotted using Matlab to analyse the results
26
Mattsson, Tommy. "A Peer-To-Peer based chat system". Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-173704.
Testo completoAbstract (sommario):
Chat systems has been around since even before the modern Internet came into existence. Today there are a variety of chat systems of varying complexity. Most of these chat systems require that a user creates an account to be used with the provided service. There has been a lot of research when it comes to networks, network communication and the use of Peer-To-Peer software has become increasingly popular. This report describes one possible way to implement a chat system using a Peer-To-Peer model instead of a client/server model without the need to sign up for the specified service to be able to use it.
27
Boldt, Martin, e Johan Wieslander. "Investigating Spyware in Peer-to-Peer Tools". Thesis, Blekinge Tekniska Högskola, Institutionen för programvaruteknik och datavetenskap, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2293.
Testo completoAbstract (sommario):
Peer-to-Peer (P2P) tools are used exclusively when their users are connected to the Internet, thus constituting a good foundation for online commercials to help finance further tool development. Although software that displays ads (adware) is very common, activity monitoring or information collecting software that spies on the users (spyware) may be installed together with the P2P tool. This paper will present a method for examining P2P tool installations and present test results from a few of the most common P2P tools. It will also discuss whether these tools, with their bundled software, make any privacy intrusions. Finally, the method itself will be evaluated and suggestions of refinements will be proposed.
28
Wan, Awang Wan Suryani. "Replica placement in peer-to-peer systems". Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/96581/.
Testo completoAbstract (sommario):
In today’s distributed applications, replica placement is essential since moving the data in the vicinity of an application will provide many benefits. The increasing requirements of data for scientific applications and collaborative access to these data make data placement even more important. Until now, replication is one of the main mechanisms used in distributed data whereby identical copies of data are generated and stored at various distributed sites to improve data access performance and data availability. Most work considers file’s popularity as one of the important parameters taken into consideration when designing replica placement strategies. However, this thesis argues that a combination of popularity and affinity files are the most important parameters which can be used in decision making whilst improving data access performance and data availability in distributed environments. A replica placement mechanism called Affinity Replica Placement Mechanism (ARPM) is proposed focusing on popular files and affinity files. The idea of ARPM is to improve data availability and accessibility in peer-to-peer (P2P) replica placement strategy. A P2P simulator, PeerSim, was used to evaluate the performance of this dynamic replica placement strategy. The simulation results demonstrated the effectiveness of ARPM hence provided a proof that ARPM has contributed towards a new dimension of replica placement strategy that incorporates the affinity and popularity of files replicas in P2P systems.
29
Luan, Hao. "Peer-to-peer content distribution network design /". View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?ECED%202007%20LUAN.
Testo completo
30
Brinkel, Guido. "Filesharing : Verantwortlichkeit in Peer-to-Peer-Tauschplattformen". Tübingen Mohr Siebeck, 2006. http://bvbr.bib-bvb.de:8991/F?func=service&docl̲ibrary=BVB01&docn̲umber=014630106&linen̲umber=0001&funcc̲ode=DBR̲ECORDS&servicet̲ype=MEDIA.
Testo completo
31
Saddi, Oualid. "Métrologie dans les réseaux Peer-To-Peer". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2007. http://tel.archives-ouvertes.fr/tel-00803195.
Testo completoAbstract (sommario):
Cette thèse s'inscrit dans le domaine de la métrologie du trafic Internet. Nous portons dans notre étude un intérêt particulier au trafic peer-to-peer (p2p) et plus précisément le trafic eDonkey, principale composante du trafic dans les réseaux de France Telecom. Nous avons analysé les différentes méthodes d'identification du trafic p2p afin d'extraire cette importante composante du trafic. Après avoir obtenu une proportion de trafic jugée représentative de l'échantillon de la population eDonkey étudiée, nous avons étudié les caractéristiques en termes de trafic de cette composante p2p en utilisant entre autres la dichotomie souris/éléphant. Outre les caractéristiques du trafic, nous avons également analysé la topologie du réseau eDonkey dans le réseau de France Telecom à l'échelle nationale et internationale. Un modèle mathématique décrivant la manière avec laquelle le réseau eDonkey se construit est également présenté.
32
Alhaisoni, Majed Mohaia. "Video streaming using peer-to-peer networks". Thesis, University of Essex, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528853.
Testo completo
33
Ieong, Sze-chung Ricci, e 楊思聰. "Analysis of peer-to-peer investigation model". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50662247.
Testo completoAbstract (sommario):
Peer-to-Peer (P2P) file sharing is one of the most commonly used methods for sharing files over a network, especially large files such as videos or music recordings. In North America, P2P file-sharing networks occupied approximately 50% of the network traffic in 2011 [3]. Many files shared through P2P networks are related to Internet piracy or unintentional file sharing. Foxy P2P network, a typical search-based P2P network, is in the spotlight for sensitive file sharing. Peers download the files by using keywords instead of resource links. Therefore, the investigation mechanisms developed to identify the first seeder in Bit-Torrent network – another type of P2P network [54], cannot be applied to this scenario.
Identifying the first seeder is the critical step in P2P investigation. The investigator cannot collect necessary evidence without locating the first seeder. Therefore, conducting forensic analysis is impossible. Moreover, validating the actual first seeder will be challenging when more than one uploader is identified.
This study started by analyzing different P2P networks and comparing their underlying features. Categorizing the P2P file-sharing networks resulted in the identification of the key functions for file sharing. Two difficulties in Foxy network investigation, namely, unknown file publication time and uncertainty of network coverage by uploaders and downloaders, were also highlighted.
To further examine the Foxy P2P network, a controlled testing environment for the P2P network was developed in a network simulation environment (i.e., NS-3). Tests were conducted in the simulation environment, and the effects of various attributes (file size, file transfer rate, file popularity) on the growth of the number of uploaders (represented by the seeder curve) were analyzed.
Results demonstrated that the shape of the seeder curve was affected by the file propagation feature of the file-sharing activity. The slow-rising period, which represented the competition for the file content being shared among peers, was recorded at the initial stage of file sharing in the P2P network. Competition for file content is one of the key factors related to the success or failure in performing P2P investigation through the simulation environment.
An investigation algorithm and four validation rules were proposed based on the above key factor to perform P2P investigation. Through controlled and randomly selected experiments, the investigation could be applied to the search-based P2P file-sharing environment as long as the required slow-rising period in other P2P networks was followed [68].
Analysis of the experimental results demonstrated the ability of the proposed investigation model and the validation rules. The results verified and confirmed the observed seeder in the P2P file-sharing scenario if competitions among downloaders for the shared file content existed. The limitations of the P2P investigation and validation model were also discussed.published_or_final_version
Computer Science
Doctoral
Doctor of Philosophy
34
Freedman, Michael J. (Michael Joseph) 1979. "A peer-to-peer anonymizing network layer". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87212.
Testo completoAbstract (sommario):
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (leaves 51-53).
by Michale J. Freedman.
M.Eng.
35
Schmidt, Justin Michael 1979. "A framework for peer-to-peer applications". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/87886.
Testo completoAbstract (sommario):
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (p. 79-82).
by Justin Michael Schmidt.
M.Eng.
36
Gupta, Anjali 1980. "Efficient routing for peer-to-peer systems". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28553.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 51-55).
This thesis examines the problem of locating and accessing an item stored in a large and volatile peer-to-peer system, and presents new ways of organizing items and peers to make this operation fast and efficient. Current structured peer-to-peer routing schemes keep routing information about only a small number of peers in the system, typically logarithmic in the size of the system. They do this under the assumption that it is infeasible to keep more routing information up-to-date since the system is highly volatile. As a result, when a node wants to locate an item, several peers have to be contacted in sequence before enough information is available to determine the location of the item. This makes routing a very long operation. In this thesis, we question this assumption and present two fast peer-to-peer routing algorithms. First, we present a "one hop" routing scheme. We show how to disseminate information about membership changes quickly enough so that peers maintain accurate routing tables with information about all peers in the system. Further, we demonstrate the feasibility of the system with analytical results and simulations. Second, we propose a "two hop" routing scheme for large scale systems of more than a few million peers, where the bandwidth requirements of one hop routing can become too large. This scheme keeps a fixed fraction of the total routing state on each peer, chosen such that the additional delay of routing is minimal.
by Anjali Gupta.
S.M.
37
Kortick, David N. "PEER-TO-PEER NETWORKING WITH TELEMETRY RECORDERS". International Foundation for Telemetering, 2003. http://hdl.handle.net/10150/605834.
Testo completoAbstract (sommario):
International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, NevadaTelemetry recorders have historically been used as standalone systems with each user responsible for operation and data interpretation on that system. Utilizing the latest peerto- peer networking technologies, telemetry recorders can now be linked to provide instantaneous communication between systems. This fully distributed, network-based architecture can be used for command and control of multiple recorders, as well as message passing between them. A centralized server is no longer required, resulting in considerable logistical and cost savings. The peer-to-peer communication topology can efficiently connect telemetry recorder “islands of information”.
38
Kolweyh, Magnus, e Ulrike Lechner. "Data Mining in Peer-to-Peer-Systemen". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-204298.
Testo completoAbstract (sommario):
Aus der Einleitung:
"Neben „klassischen“ virtuellen Gemeinschaften, die einen gemeinsamen Netzort für die Interaktion benutzen und die auf technischer Ebene vornehmlich durch den Einsatz von Client-Server-Architekturen gekennzeichnet sind, lassen sich Gemeinschaftsformen identifizieren, deren Ursprung in vollkommen dezentralen Peer-to-Peer (P2P)-Netzen liegt. Diese P2P-Gemeinschaften haben in einigen Anwendungsgebieten wie dem Filesharing großen Erfolg [SF02]."
39
Mishra, Jayant. "P2PCompute - A Peer-to-Peer Computing Model". UNF Digital Commons, 2006. http://digitalcommons.unf.edu/etd/244.
Testo completoAbstract (sommario):
Peer-to-peer (P2P) networks consist of nodes which have both client and server capabilities and on which communication and data sharing is carried on directly between nodes, rather than being arbitrated by an intermediary node. The P2P architecture was popularized by file-sharing, one of the widely-used applications of the Internet. Many applications that are based on this architecture have been developed. It also provides an efficient platform to harness the computing power of a network of desktop computers. P2P computing power can help solve computationally complex problems that require powerful supercomputers. However, it has not been as widely used as the file-sharing P2P applications. Almost all of the current P2P computing applications are noncommercial endeavors. Users make their computing power available for these endeavors because they believe in the applications' objectives, for example, the SETI project analyzes radio telescope data in the quest for life in other parts of the universe.
This thesis proposes P2PCompute - a viable commercial model in the P2P computing field. It harnesses existing technologies- P2P, Java, the Internet and the UDDI registry, to enable distributed processing of tasks on multiple servers. It is well-suited to the heterogeneous environment on the Internet and has the potential to provide the spark that would lead to the development of more commercial P2P computing applications.
40
Marco, Arranz Carlos Aurello. "IP Telephony : Peer-to-peer versus SIP". Thesis, KTH, Mikroelektronik och Informationsteknik, IMIT, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-92288.
Testo completoAbstract (sommario):
In recent years dramatic technology developments have exploited the development of better transmission media and allowed for broad internet penetration. This in turn has fostered the growth of IP telephony calls, i.e., Voice over IP (VoIP). New VoIP products are introduced almost daily, each seeking an opportunity in the market. Some of these products are free - thus putting pressure on other vendors. A good example of a commercial VoIP product is Skype. It is possibly the most important one as it has gained more than 3 millions users in approximately 2 years time. In contrast, Minisip is a non-commercial implementation of SIP developed by students at KTH. These programs are based on different architectures. While Skype is said to be based on a peer-to-peer protocol, Minisip utilized the Session Initiation Protocol (SIP) protocol. The aim of this thesis was to evaluate these two VoIP programs not only in terms of development, but also in terms of the quality of service and user perceived voice quality. The study of efficiency, usability, and installation of both are also in the scope of this thesis. The devices used for the evaluation included a HP iPAQ 5550, two PCs running in RedHat Linux 9, and a laptop running Microsoft Windows XP.På senare år har den dramatiska teknikutvecklingen exploaterat utvecklingen av bättre överföringsmedia samt möjliggjort för en bred Internetpenetrering. Det i sin tur har gynnat ökningen av telefonsamtal med IP-telefoner, d.v.s. Voice over IP (VoIP). Nya VoIP produkter introduceras nästan dagligen och varje produkt söker sin möjlighet på marknaden. Vissa av dessa produkter är gratis och sätter alltså press på andra försäljarna. Ett bra exempel på en VoIP produkt är Skype. Det är möjligtvis den viktigaste produkten då den har fått tre miljoner användare på ungefär två års tid. I kontrast till detta finns Minisip som är en icke kommersiell implementation av SIP, utvecklad av studenter från KTH. Dessa program är baserade på olika arkitekturer. Medan Skype är baserat på ett peer-to-peer protokoll, utnyttjar Minisip protokollet Session Initiation Protocol (SIP) Protocol. Syftet med denna avhandling var att evaluera dessa två VoIP program, inte bara i termer av utveckling utan också i termer av ”quality of service” och hur användaren uppfattar röstkvaliteten. Studien innefattar också effektivitet, användarvänlighet och installation av de båda programmen. Enheterna som användes under denna evaluering var en HP iPAQ 5550, två pc:s med Linux Red Hat 9 samt en bärbar pc med Windows XP.
41
Kolweyh, Magnus, e Ulrike Lechner. "Data Mining in Peer-to-Peer-Systemen". Technische Universität Dresden, 2004. https://tud.qucosa.de/id/qucosa%3A29570.
Testo completoAbstract (sommario):
Aus der Einleitung:
"Neben „klassischen“ virtuellen Gemeinschaften, die einen gemeinsamen Netzort für die Interaktion benutzen und die auf technischer Ebene vornehmlich durch den Einsatz von Client-Server-Architekturen gekennzeichnet sind, lassen sich Gemeinschaftsformen identifizieren, deren Ursprung in vollkommen dezentralen Peer-to-Peer (P2P)-Netzen liegt. Diese P2P-Gemeinschaften haben in einigen Anwendungsgebieten wie dem Filesharing großen Erfolg [SF02]."
42
Mohd, Nor Rizal. "ROBUST LOW ATOMICITY PEER-TO-PEER SYSTEMS". Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1340903594.
Testo completo
43
Tomozei, Dan-Cristian. "Distributed algorithms for peer-to-peer networks". Paris 6, 2011. http://www.theses.fr/2011PA066059.
Testo completoAbstract (sommario):
La thèse comporte trois parties. Chaque partie est consacrée à un problème algorithmique important pour les réseaux pair-à-pair. Dans la première partie on analyse des méthodes distribuées cherchant à caractériser les préférences d'usagers: On étend l'applicabilité des méthodes spectrales pour la récupération de structures cachées à des modèles probabilistes de faible rang pour les goûts des usagers. Par la suite, on propose une méthode distribuée basée sur des échanges de messages (message passing) à deux échelles séparées de temps, qui effectue le profilage des usagers d'un réseau pair-à-pair. On montre que cette méthode converge presque sûrement vers les vecteurs propres d'une matrice de similitude des usagers. Dans la deuxième partie on considère le problème d'estimation de distances dans Internet et de sélection de serveur à base d'un faible nombre de mesures. On attribue à chaque noeud des coordonnées virtuelles dans un certain espace de faible dimension et on utilise une fonction de pseudo-distance dans cet espace afin d'estimer des latences et des débits. Supposant que les mesures sont des distorsions de quantités métriques, on caractérise les performances d'une méthode simple pour l'estimation de latences. On montre également qu'il est possible d'avoir des estimations exactes des débits, si le routage suit le chemin de débit maximal. Dans la troisième partie on propose et on analyse une méthode distribuée pour control de flux dans les réseaux pair-à-pair de live-streaming qui prend en compte les couts réseau. On montre qu'une telle approche est optimale dans le cas ou les pairs implémentent le Network Coding.
44
Ferreira, Carlos André Marques Viana. "Peer-to-peer network for medical imaging". Master's thesis, Universidade de Aveiro, 2010. http://hdl.handle.net/10773/5004.
Testo completoAbstract (sommario):
Mestrado em Engenharia de Computadores e TelemáticaNos últimos anos, a imagem médica em formato digital tem sido uma ferramenta cada vez mais importante quer para o diagnóstico médico quer para o auxílio ao tratamento. Assim, equipamentos de aquisição digital e repositórios de imagem médica são cada vez mais comuns em instituições de saúde, podendo até haver mais que um repositório numa instituição. No entanto, esta proliferação de repositórios leva a que a informação esteja dispersa nos vários locais. Esta dispersão da informação juntamente com as diferenças no armazenamento entre instituições são claros obstáculos à pesquisa e acesso integrado a essa informação. Esta dissertação visa o estudo da tecnologia Peer-to-Peer de forma a minimizar os problemas associados à dispersão e heterogeneidade da informação.
In the last years, digital medical imaging has been an increasingly important tool for both medical diagnostic and treatment assistance. Therefore, digital image acquisition equipments and medical imaging repositories are more and more common in a healthcare institution, being possible even more than one repository in one institution. However, this proliferation of repositories leads to dispersion of data between many places. This data dispersion associated with differences in the data storage between institutions are evident obstacles to the search for medical data. This dissertation aims to the study of the Peer-to- Peer technology in order to minimize the problems related to the dispersion and heterogeneity of medical data.
45
Pereira, Marco Filipe Nunes Soares Abrantes. "Tecnologia peer-to-peer para bibliotecas digitais". Master's thesis, Universidade de Aveiro, 2008. http://hdl.handle.net/10773/2012.
Testo completoAbstract (sommario):
Mestrado em Engenharia de Computadores e TelemáticaAs tecnologias peer-to-peer apresentam uma forma interessante de explorar recursos computacionais normalmente desperdiçados. Esta dissertação tem como objectivo avaliar a utilização de tecnologias peer-to-peer como suporte para bibliotecas digitais. Foi utilizada a biblioteca JXTA para criar a rede peer-to-peer. Foi também definida a estratégia para a disponibilização de serviços na rede utilizando um sistema análogo aos tradicionais WebServices baseada na biblioteca JXTA-SOAP. ABSTRACT: Peer-to-peer technologies present an interesting way of exploring usually wasted resources. This dissertation’s objective is to evaluate the use of peer-to-peer technologies as a support for digital libraries. The JXTA library was used to create the peer-to-peer network. It was also defined a WebServices like strategy for services availability in the network based on the JXTA-SOAP library.
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Valiveti, Kalyan. "Agent Extensions for Peer-to-Peer Networks". Thesis, University of North Texas, 2003. https://digital.library.unt.edu/ark:/67531/metadc4382/.
Testo completoAbstract (sommario):
Peer-to-Peer (P2P) networks have seen tremendous growth in development and usage in recent times. This attention has brought many developments as well as new challenges to these networks. We will show that agent extensions to P2P networks offer solutions to many problems faced by P2P networks. In this research, an attempt is made to bring together JXTA P2P infrastructure and Jinni, a Prolog based agent engine to form an agent based P2P network. On top of the JXTA, we define simple Java API providing P2P services for agent programming constructs. Jinni is deployed on this JXTA network using an automated code update mechanism. Experiments are conducted on this Jinni/JXTA platform to implement a simple agent communication and data exchange protocol.
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Widmaier, Jochen. "Identitäts-Management in Peer-2-Peer-Umgebungen". [S.l. : s.n.], 2003. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11144229.
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Asís, López Fuentes Francisco de. "Video multicast in peer-to-peer networks". München Verl. Dr. Hut, 2009. http://d-nb.info/992892244/04.
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Magharei, Nazanin 1979. "Peer-to-peer streaming: Design and challenges". Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/11089.
Testo completoAbstract (sommario):
xxii, 413 p. : ill.Streaming multimedia content over the Internet is extremely popular mainly due to emerging applications such as IPTV, YouTube and e-learning. All these applications require simultaneous streaming of multimedia content from one or multiple sources to a large number of users. Such applications impose unique requirements in terms of server bandwidth and playback delay which are difficult to achieve in a scalable fashion with the traditional client-server architecture. Peer-to-peer (P2P) overlays offer a promising approach to support scalable streaming applications, that we broadly refer to as "P2P streaming". Design of a scalable P2P streaming mechanism that accommodates heterogeneity of peers' bandwidth and copes with dynamics of peer participation while ensuring in-time delivery of the multimedia content to individual peers is extremely challenging. Besides these fundamental challenges, P2P streaming applications are facing practical issues such as encouraging peers' contribution and decreasing the costly inter-ISP P2P traffic. In this dissertation, we study several aspects of live P2P streaming with the goal of improving the performance of such systems. This dissertation can be categorized into two parts as follows. ( i ) We present the design and evaluation of a mesh-based live P2P streaming mechanism, called PRIME. Further, we perform a head-to-head comparison between the two approaches on live P2P streaming, namely tree-based and mesh-based. We demonstrate the superiority of the mesh-based approach. In the quest for a systematic comparison of existing mesh-based solutions on live P2P streaming, we leverage the insights from our design in PRIME and propose an evaluation methodology. Utilizing the evaluation methodology, we compare the performance of existing mesh-based live P2P streaming solutions. ( ii ) From a more practical perspective, we tackle some of the existing practical issues in the deployment of live P2P streaming applications, namely providing incentives for participating peers to contribute their resources and designing ISP-friendly live P2P streaming protocols with the ultimate goal of reducing costly inter-ISP traffic. In the end, this dissertation reveals fundamental trade-offs in the design, comparison and meaningful evaluation of basic and practical live P2P streaming mechanisms under realistic settings. This dissertation includes my previously published and my co-authored materials.
Committee in charge: Prof. Reza Rejaie, Chair; Prof. Virginia Lo; Prof. Jun Li; Prof. David Levin; Prof. Markus Hofmann
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Pack, Roger D. "Automatic Transition to Peer-to-Peer Download". BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2218.
Testo completoAbstract (sommario):
For traditional web servers, available bandwidth decreases as the number of clients increases. This can cause servers to serve files slowly or to become completely overwhelmed when load grows too high. BitTorrent is a peer-to-peer solution to this problem, but it requires manual configuration for each file to be delivered this way. We develop a new system that integrates peer-to-peer file delivery with traditional client-server downloads. Clients initially attempt to download a file from a web server; if this is too slow, they transition to peer-to-peer delivery. Experiments with a prototype system show that it serves up to 30x faster than traditional web servers.