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Abstract: In Technics and Time, 1, Bernard Stiegler (1998) challenged the prevalent philosophical distinction between tekhnē and ēpistēmē, arguing that humans are fundamentally technical beings. According to Stiegler, the industrialization of civilization led to a disequilibrium in the evolution of culture and the evolution of technics, with technics evolving more quickly than culture. Stiegler''s discussions of technics, culture, time, and memory provide a useful theoretical framework for understanding some of the cultural implications of copyright issues, which are often viewed in terms of economics, legality, and/or ethics. In this article, I focus on the intellectual property debate as it pertains to peer-to-peer networks and the music industry. Drawing from Technics and Time, I theoretically frame these issues as a problem of temporality, memory, and a disconnect in the evolution of culture and technology. I then use small-scale/observational ethnographic analysis to examine a private torrent community to consider how torrent communities are cultural phenomena, the implications of this assumption, and how these considerations might inform or extend existing approaches to issues of intellectual property. More broadly, I ask, what are the affordances of thinking about these economic, legal, and political issues from a cultural framework? [Copyright &y& Elsevier]

This paper presents an efficient approach for improving file availability in super-peer-based peer-to-peer (P2P) file-sharing systems. In the super-peer-based P2P file-sharing system, peers are organized into multiple groups. In each group, there is a special peer called super-peer to serve the regular peers within the same group. With this property, the proposed approach utilizes the super-peer to tolerate the departure (failure) of a regular peer in order to protect shared files. Unlike traditional replication-based approaches, the proposed approach keeps track of the file queries in the super-peer to support fault tolerance. The cost of tracking the file queries is much smaller than the cost of replicating the file contents in advance. Furthermore, the proposed approach uses a logical connection technique to consider the departure (failure) of the super-peer. Finally, simulation experiments are performed to quantify the performance and overhead of the proposed approach. [ABSTRACT FROM PUBLISHER]

Peer-to-peer systems provide scalable content distribution for cheap and resist to censorship attempts. However, P2P networks mainly distribute immutable content and provide poor support for highly dynamic content such as produced by collaborative systems. A new class of algorithms called CRDT (Commutative Replicated Data Type), which ensures consistency of highly dynamic content on P2P networks, is emerging. However, if existing CRDT algorithms support the "edit anywhere, anytime" feature, they do not support the "undo anywhere, anytime" feature. In this paper, we present the Logoot-Undo CRDT algorithm, which integrates the "undo anywhere, anytime" feature. We compare the performance of the proposed algorithm with related algorithms and measure the impact of the undo feature on the global performance of the algorithm. We prove that the cost of the undo feature remains low on a corpus of data extracted from Wikipedia. [ABSTRACT FROM AUTHOR]

Abstract: In vehicular ad hoc networks (VANETs), different types of information can be useful to drivers. Such networks are highly dynamic due to both the movements of the vehicles and the short range of the wireless communications. Thus, the information exchanges between vehicles about relevant information can only rely on short interactions. Therefore, an efficient mechanism to manage and disseminate the relevant information is required. Specifically, we present in this paper a system for data sharing in vehicular networks, which we call Vehicular Event Sharing with a mobile Peer-to-peer Architecture (VESPA). In this system, a new technique based on the concept of Encounter Probability is proposed for vehicles to share information using vehicle-to-vehicle communications. The objective is to facilitate the dissemination of information between vehicles when they meet each other, taking into account the relevance of the data to the drivers. Besides, the relevance must also be considered to inform a driver about the interesting events. Moreover, our proposal takes into account any type of event (e.g., available parking spaces, obstacles in the road, information relative to the coordination of vehicles in emergency situations, etc.) in the network. An experimental evaluation and the implemented prototype show the interest of the system. [Copyright &y& Elsevier]

In peer-to-peer (P2P) on-demand streaming networks, the alleviation of server load depends on reciprocal stream sharing among peers. In general, on-demand video services enable clients to watch videos from beginning to end. As long as clients are able to buffer the initial part of the video they are watching, on-demand service can provide access to the video to the next clients who request to watch it. Therefore, the key challenge is how to keep the initial part of a video in a peer's buffer for as long as possible, and thus maximize the availability of a video for stream relay. In addition, to address the issues of delivering data on lossy network and providing scalable quality of services for clients, the adoption of multiple description coding (MDC) has been proven as a feasible resolution by much research work. In this paper, we propose a novel caching scheme for P2P on-demand streaming, called Dynamic Buffering. The proposed Dynamic Buffering relies on the feature of MDC to gradually reduce the number of cached descriptions held in a client's buffers, once the buffer is full. Preserving as many initial parts of descriptions in the buffer as possible, instead of losing them all at one time, effectively extends peers' service time. In addition, this study proposes a description distribution balancing scheme to further improve the use of resources. Simulation experiments show that Dynamic Buffering can make efficient use of cache space, reduce server bandwidth consumption, and increase the number of peers being served. [ABSTRACT FROM AUTHOR]

In this paper, according to the information security in enterprises, campuses and other organizations and institutions, an P2P-based network confidential inspection system NSSP is proposed. It combines the unstructured and structured P2P networks, positioning nodes rapidly, querying for data on the hard disk effectively and timely to achieve confidential inspection. [ABSTRACT FROM AUTHOR]

With the fast development of IT technologies, virtual organizations are more and more present in the current collaborative work and learning activity. For instance, many subjects in virtual distance learning are organized as online groups of students, who use groupware tools to complete their learning tasks. In this paper, we address the efficient management of peer groups in JXTA-based P2P systems as a key issue in many P2P applications that use peer group as a unit such as for remote execution of tasks in parallel and distributed applications. From this perspective, we consider peer grouping as the basis in the development of groupware tools in P2P systems. Motivated by the need to support online teams of real virtual campuses, in this work we propose the management of peer groups in JXTA-Overlay, a JXTA-based P2P middleware for the development of P2P applications. To this end, by taking advantage of the peerGroup entity in JXTA library we have designed and implemented a set of primitives as part of JXTA-Overlay aiming to support efficient peer group management. We show the usefulness of using JXTA-Overlay for the development of P2P groupware tools for supporting online teams of students in a virtual campus. Our approach distinguishes from existing studies by using groupware tools in a customized way and tailored to the specific needs of small online teams of students who consider group monitoring and autonomy, confidentiality and security as important concerns. The groupware tools developed for P2P systems include instant messaging and chat rooms, task execution in peer group’s resources and file sharing system. We successfully deployed these tools based on JXTA-Overlay in a real P2P network. The experimental results showed the feasibility of our approach when applied to small groups of students who use standard desktop and laptop computers and have rather limited bandwidth of Home Net connections. On the other hand, the JXTA library showed some performance limitations, such as CPU consumption, when using the P2P file sharing system and sharing about three hundred files among all peers of a real small network made up of limited computational resources and rather small bandwidth. [ABSTRACT FROM AUTHOR]

In large-scale peer-to-peer (P2P) video-on-demand (VoD) streaming applications, a fundamental challenge is to quickly locate new supplying peers whenever a VCR command is issued, in order to achieve smooth viewing experiences. For many existing commercial systems which use tracker servers for neighbor discovery, the increasing scale of P2P VoD systems has overloaded the dedicated servers to the point where they cannot accurately identify the suppliers with the desired content and bandwidth. To avoid overloading the servers and achieve instant neighbor discovery over the self-organizing P2P overlay, we design a novel method of organizing peers watching a video. The method features a light-weight indexing architecture to support efficient streaming and fast neighbor discovery at the same time. InstantLeap separates the neighbors at each peer into a streaming neighbor list and a shortcut neighbor list, for streaming and neighbor discovery respectively, which are maintained loosely but effectively based on random neighbor list exchanges. Our analysis shows that InstantLeap achieves an O(1) neighbor discovery efficiency upon any playback “leap” across the media stream in streaming overlays of any size, and low messaging costs for overlay maintenance upon peer join, departure, and VCR operations. We also verify our design with large-scale simulation studies of dynamic P2P VoD systems based on real-world settings. [ABSTRACT FROM AUTHOR]

A conference paper on the development of the Hellenic National Audiovisual Archive (HeNAA) as a Digital Library (DL) in relation to the use peer-to-peer (P2P) computer file sharing is presented. It says that the architecture of HeNAA digital library relies heavily on P2P. However, it says that P2P is seen by Copyright holders as detrimental for their individual business interests. It also asserts that legislations should be passed which consider the importance of the noncommercial role of P2P.

We study competitive interaction between two alternative models of digital content distribution over the Internet: peer-to-peer (p2p) file sharing and centralized client–server distribution. We present microfoundations for a stylized model of p2p file sharing where all peers are endowed with standard preferences and show that the endogenous structure of the network is conducive to sharing by a significant number of peers, even if sharing is costlier than freeriding. We build on this model of p2p to analyze the optimal strategy of a profit-maximizing firm, such as Apple, that offers content available at positive prices. We characterize the size of the p2p network as a function of the firm's pricing strategy, and show that the firm may be better off setting high prices, allowing the network to survive, and that the p2p network may work more efficiently in the presence of the firm than in its absence. [ABSTRACT FROM AUTHOR]

In this paper, we study p2p systems, where peers have to share their available resources between their own and other peers' needs. One such example is a system of peers who use their capacity-limited access links both for their upstream and downstream connections. In the selfish approach, each peer would like to exploit the full capacity of his access link only for his downloads. However, if all peers acted selfishly, the system would collapse. In order to motivate peers to cooperate, we propose a distributed reputation-based system according to which peers earn reputation analogous to their contributions. In this way, each peer has to trade off the capacity he will dedicate for uploading in order to increase his reputation and therefore his revenue and the capacity he will dedicate for his downloads. All peers act rationally, trying to maximize their utility. Our proposed policies lead rational peers to cooperation while promoting fairness, as peers receive resources in proportion to their contributions. Our policies outperform existing work in this area in which the slowest link becomes the bottleneck of a heterogeneous system of different link capacity peers. On the contrary, no such bottleneck appears when our policies are used, improving the performance of the system. Finally, we apply our reputation-based approach in a BitTorrent-like file sharing system and we highlight the potential performance gains. [ABSTRACT FROM AUTHOR]

In control system, tag table is like a dictionary mapping tagname to address. Therefore, applications on workstation may use tagname to access different data in system. Normally tag table generated by configuration software will transfer to other workstation in system manually after system configuration, which is inconvenient and fallible. The development of peer-to-peer (P2P) network technology and the realization of control system based on P2P network make the auto distribution of tag table possible. In this paper based on file sharing technology the presented method realizes the auto distribution of tag table. [ABSTRACT FROM AUTHOR]

Wireless mesh networks are a promising area for the deployment of new wireless communication and networking technologies. In this paper, we address the problem of enabling effective peer-to-peer resource sharing in this type of networks. Starting from the well-known Chord protocol for resource sharing in wired networks, we propose a specialization that accounts for peculiar features of wireless mesh networks: namely, the availability of a wireless infrastructure, and the 1-hop broadcast nature of wireless communication, which bring to the notions of location awareness and MAC layer cross-layering. Through extensive packetlevel simulations, we investigate the separate effects of location awareness and MAC layer cross-layering, and of their combination, on the performance of the P2P application. The combined protocol, MESHCHORD, reduces message overhead of as much as 40 percent with respect to the basic Chord design, while at the same time improving the information retrieval performance. Notably, differently from the basic Chord design, our proposed MESHCHORD specialization displays information retrieval performance resilient to the presence of both CBR and TCP background traffic. Overall, the results of our study suggest that MESHCHORD can be successfully utilized for implementing file/resource sharing applications in wireless mesh networks. [ABSTRACT FROM AUTHOR]

The open literature contains numerous studies of capacity bounds for an N-node wireless ad-hoc network but the number of cooperating nodes has generally been limited to two. In this paper, we present a simple time-share lower bound for such a network, but with two or more cooperating nodes. These results are then compared against our previous information theoretic upper bounds with hop-by-hop routing, frequency reuse, and no cooperation. While simulations show that our simple time-share lower bound with cooperation does not outperform our previous upper bound without cooperation, we do note a significant increase in achievable capacity relative to time-share results without cooperation. Also, our results indicate that there is no significant improvement when more than two nodes cooperate. [ABSTRACT FROM AUTHOR]

Peer-to-peer (P2P) networks are very popular for large-scale data sharing in today's internet. It is naturally envisioned that the file sharing would also be an important application for civil mobile ad hoc networks in the future. The authors propose the cooperative diversity download methods utilising the wireless medium and common file sources in wireless P2P networks. The designed protocols including multi-source opportunistic direct downloading (MODD) and multi-source opportunistic decode-and-forward downloading (MODFD) can adaptively work in different file distribution scenarios. Both of them rely on the cooperation between the sources or receivers and the proposed distributed source-selection schemes. For the situation with one receiver and multi-source, MODD selects ‘best’ source with most favourite channel condition from available m sources. In the situation with multiple receivers and sources, the multiple receivers could form the cooperative pairs to receive the data from the selected source based on decode-and-forward transmission strategy. Compared with MODD, MODFD saves the source-selection time and provides incentives for the cooperation between the peers. A distributed collision solving scheme for the selection schemes is also proposed. The information theoretic analysis of outage probability shows that the proposed downloading methods can both obtain m times diversity gain. [ABSTRACT FROM AUTHOR]

Understanding the social impact of advanced access technologies and witnessing that applications are increasingly based on content providedby end users, we take a look at next-generation EPON networks and elaborate on their suitability to efficiently support online gaming and P2P file sharing applications by means of evolutionary WDM and long-reach PON upgrades. We examine a scalable all-optical integration of WDM EPONs, which exploits the unique traffic characteristics of P2P file sharing and online gaming applications, and supports them with an incremental add-on service with fallback option. [ABSTRACT FROM AUTHOR]

In peer-to-peer file sharing systems, file replication and consistency maintenance are widely used techniques for high system performance. Despite significant iriterdependencies between them, these two issues are typically addressed separately. Most file replication methods rigidly specify replica nodes, leading to low replica utilization, unnecessary replicas and hence extra consistency maintenance overhead. Most consistency maintenance methods propagate update messages based on message spreading or a structure without considering file replication dynamism, leading to inefficient file update and hence high possibility of outdated file response. This paper presents an Integrated file Replication and consistency Maintenance mechanism (IRM) that integrates the two techniques in a systematic and harmonized manner. It achieves high efficiency in file replication and consistency maintenance at a significantly low cost. Instead of passively accepting replicas and updates, each node determines file replication and update polling by dynamically adapting to time-varying file query and update rates, which avoids unnecessary file replications and updates. Simulation results demonstrate the effectiveness of IRM in comparison with other approaches. It dramatically reduces overhead and yields significant improvements on the efficiency of both file replication and consistency maintenance approaches. [ABSTRACT FROM AUTHOR]

In wireless mobile peer-to-peer (P2P) networks, multiple sources can provide multimedia file sharing at the same time. The selection of multiple sources is one of the key issues in the design of a multisource-transmission system in wireless mobile P2P networks. In this paper, we propose a distributed multisource sender-selection scheme to maximize the receiving data rate and minimize the energy consumption. Our scheme is based on recent advances in restless-bandit algorithms. The proposed sender-selection scheme has an indexability property that dramatically simplifies the computation and implementation of the policy. In addition, there is no need for a centralized control point, and senders can freely join and leave from the wireless mobile P2P network. Simulation results show that the proposed scheme significantly improves the receiving data rate and energy-consumption performance compared with the existing scheme. [ABSTRACT FROM AUTHOR]

Peer-to-peer networks are often used to infringe copyrights, but they also serve some legitimate purposes consistent with copyright law. In attempting to find a satisfactory solution, this note develops and analyzes two models that future peer-to-peer networks could employ to attempt to avoid liability for copyright infringement. The note then analyzes the law, applies the two models to the relevant legal tests, and analyzes whether a peer-to-peer network operating on each model could avoid liability for copyright infringement. It concludes that modifying their technological structure may help peer-to-peer networks avoid liability, but that some risks remain. [ABSTRACT FROM AUTHOR]

Peer-to-Peer (P2P) file sharing is one of key technologies for achieving attractive P2P multimedia social networking. In P2P filesharing systems, file availability is improved by cooperative users who cache and share files. Note that file caching carries costs such as storage consumption and processing load. In addition, users have different degrees of cooperativity in file caching and they are in different surrounding environments arising from the topological structure of P2P networks. With evolutionary game theory, this paper evaluates the performance of P2P file sharing systems in such heterogeneous environments. Using micro-macro dynamics, we analyze the impact of the heterogeneity of user selfishness on the file availability and systemstability. Further, through simulation experiments with agent-based dynamics, we reveal how other aspects, for example, synchronization among nodes and topological structure, affect the system performance. Both analytical and simulation results show that the environmental heterogeneity contributes to the file availability and system stability. [ABSTRACT FROM AUTHOR]

This paper presents a solution for reducing the ill effects of free-riders in decentralised unstructured P2P networks. An autonomous replication scheme is proposed to improve the availability and enhance system performance. Q-learning is widely employed in different situations to improve the accuracy in decision making by each peer. Based on the performance of neighbours of a peer, every neighbour is awarded different levels of ranks. At the same time a low-performing node is allowed to improve its rank in different ways. Simulation results show that Q-learning-based free riding controlmechanism effectively limits the services received by free-riders and also encourages the low-performing neighbours to improve their position. The popular files are autonomously replicated to nodes possessing required parameters. Due to this improvement of quantity of popular files, free riders are given opportunity to lift their position for active participation in the network for sharing files. Q-feed effectively manages queries from free riders and reduces network traffic significantly. [ABSTRACT FROM AUTHOR]

In this work, we develop a general methodology to assess the level of network awareness and friendliness of P2P-TV applications. The methodology is based on a combination of active and passive measurement techniques and can be applied to any P2PTV system since it is designed to work considering such systems as a black-boxes. As an interesting case study, we then apply this methodology to PPLive, one of the most popular P2P-TV systems nowadays. Focusing on the video content distribution, we consider several per-path and per-peer metrics, investigating which of them mostly biases PPLive download preferences. Furthermore, in order to refine the picture of PPLive peer selection policy, we not only study the impact of different metrics in isolation, but also assess the joint impact of different metrics at the same time. Our main finding is that PPLive seems mainly bandwidth greedy, but does not show any preference toward peer proximity based on RTT delay; at the same time, our results also suggest that this choice alone may provide a nonnegligible level of geographical clustering among peers as a beneficial side effect. [ABSTRACT FROM AUTHOR]

Peer-to-peer is emerging as a potentially disruptive technology for content distribution in the mobile Internet. In addition to the already well-known peer-to-peer file sharing, real-time peer-to-peer streaming is gaining popularity. This paper presents an effective real-time peer-to-peer streaming system for the mobile environment. The basis for the system is a scalable overlay network which groups peer into clusters according to their proximity using RTT values between peers as a criteria for the cluster selection. The actual media delivery in the system is implemented using the partial RTP stream concept: the original RTP sessions related to a media delivery are split into a number of so-called partial streams according to a predefined set of parameters in such a way that it allows low-complexity reassembly of the original media session in real-time at the receiving end. Partial streams also help in utilizing the upload capacity with finer granularity than just per one original stream. This is beneficial in mobile environments where bandwidth can be scarce. [ABSTRACT FROM AUTHOR]

Estimating the global data distribution in Peer-to-Peer (P2P) networks is an important issue and has not yet been well addressed. It can benefit many P2P applications, such as load balancing analysis, query processing, data mining, and so on. In this paper, we propose a novel algorithm which is based on compact multi-dimensional histogram information to achieve high estimation accuracy with low estimation cost. Maintaining data distribution in a multi-dimensional histogram which is spread among peers without overlapping and each part of which is further condensed by a set of discrete cosine transform coefficients, each peer is capable to hierarchically accumulate the compact information to the entire histogram by information exchange and consequently estimates the global data density with accuracy and efficiency. Algorithms on discrete cosine transform coefficients hierarchically accumulating as well as density estimation error are introduced with detailed theoretical analysis and proof. Our extensive performance study confirms the effectiveness and efficiency of our methods on density estimation in dynamic P2P networks. [ABSTRACT FROM AUTHOR]

This article will address three fundamental issues (i) the impact and legal status of BitTorrent technology on copyright infringement of music, software and movies over the internet (ii) damages and the enforcement of intellectual property rights via the EC Directive and (iii) argue that damages should continue to be used as a form of deterrence to illegal file sharing and “torrents” download by the end users who are enticed in the first place by the “torrent” up loaders through their websites and internet service providers “ISP’s” who might bear indirect liability for copyright infringement. The central point is that the same manner in which taxes are due to the state and failure to render unto “Caesar” what is due will likely result in a fine or prison sentence the same approach must be taken to internet copyright infringement through file sharing and “torrents” where there is a copyright infringement. A comparison of three recent cases that were decided on the BitTorrent technology platform will be used to bolster the arguments. The article begin with an overview of legal and economic argument in the current debate on internet copyright infringement then assess the enforcement of such infringement through the EC Directive on enforcement of intellectual property and its relations to damages and then concludes with the impact on choice of law for internet copyright infringement that takes place beyond national borders. [ABSTRACT FROM PUBLISHER]

Abstract: The decentralized peer-to-peer (P2P) technique has been widely used to implement scalable file sharing systems. It organizes nodes in a system into a structured or unstructured network. The advantages of the unstructured P2P systems are that they have lower maintenance complexity and can better adapt to node heterogeneity as well as network dynamics. However, the search process in unstructured systems is not as efficient as in structured P2P systems because the same search message may go through a node multiple times. To facilitate the complex search and improve the search efficiency, we propose a novel approach of assigning identifications to nodes in an unstructured system. Our method can prevent a node from receiving duplicate search messages and retain the low maintenance overhead for the system. The performance evaluations demonstrate that the proposed approach can improve the search efficiency of unstructured P2P systems while keeping the maintenance overhead at a comparable or even lower level, compared with the traditional unstructured systems. [Copyright &y& Elsevier]

Efficient file searching is an essential feature in P2P systems. While many current approaches use brute force techniques to search files by meta information (file names, extensions or user-provided tags), the interest is in implementing techniques that allow content-based search in P2P systems. Recently, clustering techniques have been used for searching text documents to increase the efficiency of document discovery and retrieval. Integrating such techniques into P2P systems is important to enhance searching in P2P file sharing systems. While some effort has been taken for content-based searching for text documents in P2P systems, there has been few research work for applying these techniques to multimedia content in P2P systems. In this paper, we introduce two P2P content-based clustering techniques for multimedia documents. These techniques are an adaptation of the existing Class-based Semantic Search algorithm for text documents. The proposed algorithms have been integrated into a JXTA-based Overlay P2P platform, and evaluation results are provided. The JXTA-Overlay together with the considered clustering techniques is thus very useful for developing P2P multimedia applications requiring efficient searching of multimedia contents in peer nodes. [ABSTRACT FROM AUTHOR]

Peer-to-peer (P2P) file sharing is a leading Internet application. Millions of users use P2P file-sharing systems daily to search for and download files, accounting for a large portion of Internet traffic. Due to their scale, it is important to fully understand how these systems work. We analyze user queries and shared files collected on the Gnutella system, draw some conclusions on the nature of the application, and propose some research problems. [ABSTRACT FROM AUTHOR]

Existing topology-aware methods have mostly the disadvantages of consuming large. amount of bandwidth, and needing complex calculations. For the purpose of resolving these problems, multi-level chord, or MLC, was proposed as a layered physical location-aware P2P network topology. MLC used a simple method that overlay network structure constructed by directly used physical network topology. This method ensured that nodes which were closer in overlay network were nodes which were closer in physical network, while avoiding the shortcomings of existing methods. Analysis showed through the layered topology mechanism and the role of GL(Group Leader) and SL(Slice Leader), that a better balance of the load can be achieved. With the bottom-up transmitting mechanism, the searching speed improved obviously. Period partial update algorithm can reduce some of the traffic. Experiments showed that MLC is a more effective network topology which has better performance than Chord in areas of hop in logical path, delay-time of physical path and average transfer time. [ABSTRACT FROM AUTHOR]

In 3G networks upgraded with high speed packet access (HSPA) technology, the high access bandwidth and advanced mobile devices make it applicable to share large files among mobile users by peer-to-peer applications. To receive files as quickly as possible is essential for mobile users in file sharing applications, since they are subject to unstable signal strength and battery failures. While many researches present peer-to-peer file sharing architectures in mobile environments, few works focus on decreasing the time spent in disseminating files among users. In this paper, we present an efficient peer-to-peer file sharing design for HSPA networks called efficient file sharing (EFS) for 3G networks. EFS can decrease the dissemination time by efficiently utilizing the upstream-bandwidth of mobile nodes. It uses an adaptive rearrangement of a node’s concurrent uploading transfers, which causes the count of the node’s concurrent uploading transfers to lower while ensuring that the node’s upstream-bandwidth can be efficiently utilized. Our simulations show that, EFS achieves much less dissemination time than other protocols including Bullet Prime and a direct implementation of BitTorrent for mobile environments. [ABSTRACT FROM AUTHOR]

Most peer-to-peer lookup schemes keep a small amount of routing state per node, typically logarithmic in the number of overlay nodes. This design assumes that routing information at each member node must be kept small so that the bookkeeping required to respond to system membership changes is also small, given that aggressive membership dynamics are expected. As a consequence, lookups have high latency as each lookup requires contacting several nodes in sequence. In this paper, we question these assumptions by presenting a peer-to-peer routing algorithm with small lookup paths. Our algorithm, called "OneHop," maintains full information about the system membership at each node, routing in a single hop whenever that information is up to date and in a small number of hops otherwise. We show how to disseminate information about membership changes quickly enough so that nodes maintain accurate complete membership information. We also present analytic bandwidth requirements for our scheme that demonstrate that it could be deployed in systems with hundreds of thousands of nodes and high churn. We validate our analytic model using a simulated environment and a real implementation. Our results confirm that OneHop is able to achieve high efficiency, usually reaching the correct node directly 99 percent of the time. [ABSTRACT FROM AUTHOR]

Abstract  Peer-to-Peer Desktop Grid (P2PDG) has emerged as a pervasive cyber-infrastructure tackling many large-scale applications with high impacts. As a burgeoning research area, P2PDG can support numerous applications, including scientific computing, file sharing, web services, and virtual organization for collaborative activities and projects. To handle trustworthiness issues of these services, trust and reputation schemes are proposed to establish trust among peers in P2PDG. In this paper, we propose a robust group trust management system, called H-Trust, inspired by the H-index aggregation technique. Leveraging the robustness of the H-index algorithm under incomplete and uncertain circumstances, H-Trust offers a robust personalized reputation evaluation mechanism for both individual and group trusts with minimal communication and computation overheads. We present the H-Trust scheme in five phases, including trust recording, local trust evaluation, trust query phase, spatial-temporal update phase, and group reputation evaluation phases. The rationale for its design, the analysis of the algorithm are further investigated. To validate the performance of H-Trust scheme, we designed the H-Trust simulator HTrust-Sim to conduct multi-agent-based simulations. Simulation results demonstrate that H-Trust is robust and can identify and isolate malicious peers in large scale systems even when a large portion of peers are malicious. [ABSTRACT FROM AUTHOR]

We consider the problem of update processing in a peer-to-peer (P2P) database network where each peer consists of an independently created relational database. We assume that peers store related data, but data has heterogeneity wrt instances and schemas. The differences in schema and data vocabulary are bridged by value correspondences called mapping tables. Peers build an overlay network called acquaintance network, in which each peer may get acquainted with any other peer that stores related data. In this setting, the updates are free to initiate in any peer and are executed over other peers which are acquainted directly or indirectly with the updates initiator. The execution of an update is achieved by translating, through mapping tables, the update into a set of updates that are executed against the acquainted peers. We consider both the soundness and completeness of update translation. When updates are generated and propagated in the network initiated from a peer, a tree is built dynamically called Update Dependency Tree (UDT). The UDT depicts the relationships among the component updates generated from the initial update. We also discuss the issues of the update propagation when a peer is temporarily unavailable or offline. Our propagation mechanism keeps track of a peer when the peer is not available for a certain period of time and once the peer comes back online the system propagates the updates destined to the returning peer to keep it's database synchronized. Moreover, conflict detection and resolution strategies have been proposed for such a dynamic P2P database network. We have implemented and experimentally tested a prototype of our update processing mechanism on a small P2P database network. We show the results of our experiments. [ABSTRACT FROM AUTHOR]

In this letter, we consider peer-to-peer (P2P) networks, where multiple peers are interested in sharing their content. In the considered P2P system, autonomous and self-interested peers use a Markov Decision Process (MDP) framework to determine their upload bandwidth allocations, which maximize their individual utilities. This framework enables the peers to make foresighted decisions on their bandwidth allocations, by considering the future impact of their decisions. In this letter, we focus on the impact of the peers' bounded rationality on their resource reciprocation strategies and ultimately, on their achievable utilities. Specifically, we consider peers who have only a limited ability to model the other peers' strategies for resource reciprocation, and study how this impacts their own decisions. [ABSTRACT FROM AUTHOR]

This study explores file sharers' reported motivations for downloading and uploading content on peer-to-peer networks, including ethical obligations guiding file sharing. Drawing on Lessig's classification of purposes of file sharing and Giesler's theoretical framework of gifting systems, 40 in-depth interviews were conducted with file sharers in Singapore using a standard protocol, then transcripts were analyzed using qualitative content analysis. Downloading is perceived as an alternative through which users satisfy desires that existing markets do not meet. Respondents reported downloading to avoid long waits for content to arrive in Singapore; to access difficult-to-find and censored content; to sample content, including content outside their usual tastes; and because downloading is convenient and free. Respondents reported a norm of reciprocity and sense of community that motivated them to upload and an obligation to purchase content they liked. Implications for understanding and combating file sharing during the inevitable transition to other business models are discussed. [ABSTRACT FROM AUTHOR]

Data objects have to be replicated in large-scale distributed systems for reasons of fault tolerance, availability, and performance. Furthermore, computations may have to be scheduled on these objects, when these objects are part of a grid computation. Although replication mechanism for unstructured peer-to-peer (P2P) systems can place replicas on capable nodes, they may not be able to provide deterministic guarantees on searching. Replication mechanisms in structured P2P systems provide deterministic guarantees on searching but do not address node capability in replica placement. We propose Virat, a node-capability-aware P2P middleware for managing replicas in large-scale distributed systems. Virat uses a unique two-layered architecture that builds a structured overlay over an unstructured P2P layer, combining the advantages of both structured and unstructured P2P systems. Detailed performance comparison is made with a replication mechanism. realized over OpenDHT, a state-of-the-art structured P2P system. We show that the 99th percentile response time for Virat does not exceed 600 ms, whereas for OpenDHT, it goes beyond 2000 ms in our test bed, created specifically for the aforementioned comparison. [ABSTRACT FROM AUTHOR]

This paper reports on a naturalistic study of peer-to-peer learning, in a live, online video meeting context. Over a six-month period a group of international students of animation attended 99 live, online “study group” events amounting to around 120 hours of live “broadcast meeting time”. Some meetings were very large, with up to 34 participants, but the average participation was 10 students. These events were entirely self-organised, policed and managed by the student community. Some students emerged as natural mentors, and the group exhibited substantial supportive, mutually facilitative roles. This longitudinal study examines the impact of simple, live videoconferencing in an online peer learning context. The study also provides a formal measure of how learners can provide “symmetrical” support for each other in a live non-formal context, even without a formal scaffold of lectures and seminars. [ABSTRACT FROM AUTHOR]

The article discusses copyright infringement cases involving providers of Internet file-sharing services such as Napster, which enabled users to download songs from their web site for free. It also suggests the application of the concept of "modus operandi" to determine whether the accused violates copyright infringement laws. The concept of "modus operandi" can be used to prove whether the accused demonstrates a pattern of law breaking, and refine legal standards on litigations involving copyright infringement by file-sharing service providers.

Abstract: Recent progress in peer to peer (P2P) search algorithms has presented viable structured and unstructured approaches for full-text search. We posit that these existing approaches are each best suited for different types of queries. We present PHIRST, the first system to facilitate effective full-text search within P2P databases. PHIRST works by effectively leveraging between the relative strengths of these approaches. Similar to structured approaches, agents first publish terms within their stored documents. However, frequent terms are quickly identified and not exhaustively stored, resulting in a significant reduction in the system''s storage requirements. During query lookup, agents use unstructured search to compensate for the lack of fully published terms. Additionally, they explicitly weigh between the costs involved in structured and unstructured approaches, allowing for a significant reduction in query costs. Finally, we address how node failures can be effectively addressed through storing multiple copies of selected data. We evaluated the effectiveness of our approach using both real-world and artificial queries. We found that in most situations our approach yields near perfect recall. We discuss the limitations of our system, as well as possible compensatory strategies. [Copyright &y& Elsevier]

This paper presents a detailed examination of how the dynamic and heterogeneous nature of real-world peer-to-peer systems can introduce bias into the selection of representative samples of peer properties (e.g., degree, link bandwidth, number of files shared). We propose the Metropolized Random Walk with Backtracking (MRWB) as a viable and promising technique for collecting nearly unbiased samples and conduct an extensive simulation study to demonstrate that our technique works well for a wide variety of commonly-encountered peer-to-peer network conditions. We have implemented the MRWB algorithm for selecting peer addresses uniformly at random, into a tool called ion-sampler. Using the Gnutella network, we empirically show that ion-sampler yields more accurate samples than tools that rely on commonly-used sampling techniques and results in dramatic improvements in efficiency and scalability compared to performing a full crawl. [ABSTRACT FROM AUTHOR]

The BitTorrent (BT) file sharing protocol is very popular due to its scalability property and the built-in incentive mechanism to reduce free-riding. However, in designing such P2P file sharing protocols, there is a fundamental trade-off between keeping fairness and providing good performance. In particular, the system can either keep peers (especially those resourceful ones) in the system for as long as possible so as to help the system to achieve better performance, or allow more resourceful peers to finish their download as quickly as possible so as to achieve fairness. The current BT protocol represents only one possible implementation in this whole design space. The objective of this paper is to characterize the design space of BT-like protocols. The rationale for considering fairness in the P2P file sharing context is to use it as a measure of willingness to provide service. We show that there is a wide range of design choices, ranging from optimizing the performance of file download time, to optimizing the overall fairness measure. More importantly, we show that there is a simple and easily implementable design knob so that the system can operate at a particular point in the design space. We also discuss different algorithms, ranging from centralized to distributed, in realizing the design knob. Performance evaluations are carried out, both via simulation and network measurement, to quantify the merits and properties of the BT-like file sharing protocols. [ABSTRACT FROM AUTHOR]

Unstructured peer-to-peer (P2P) networks suffer from the increased volume of traffic produced by flooding. Methods such as random walks or dynamic querying managed to limit the traffic at the cost of reduced network coverage. In this paper, we propose a partitioning method of the unstructured overlay network into a relative small number of distinct subnetworks. The partitioning is driven by the categorization of keywords based on a uniform hash function. The method proposed in this paper is easy to implement and results in significant benefit for the blind flood method. Each search is restricted to a certain partition of the initial overlay network and as a result it is much more targeted. Last but not least, the search accuracy is not sacrificed to the least since all related content is searched. The benefit of the proposed method is demonstrated with extensive simulation results, which show that the overhead for the implementation and maintenance of this system is minimal compared to the resulted benefit in traffic reduction. [ABSTRACT FROM AUTHOR]

Free riding in peer-to-peer (P2P) networks poses a serious threat to their proper operation. Here, the authors present a variety of approaches developed to overcome this problem. They introduce several unique aspects of P2P networks and discuss free riding's effects on P2P services. They categorize proposed solutions and describe each category's important features and implementation issues together with some sample solutions. They also discuss open issues, including common attacks and security considerations. [ABSTRACT FROM AUTHOR]

In a number of Internet applications, we need to search for objects to download them. This includes peer-to-peer (P2P) file sharing, grid computing and content distribution networks. Here the single object will be searched for in multiple servers. There are many searching algorithms in existence today for this purpose based on the concept of classical physics and classical algorithms. The principles of quantum mechanics can be used to build and analyze a quantum computer and its algorithms. Quantum searching is such an algorithm. In this paper we are proposing a search method based on the quantum physics and quantum algorithms. Our method, the targeted quantum search is found to be more cost effective than any other classical searching algorithms like linear and two-way linear, simulated annealing, including broadcast based searching. Our targeted quantum search method is analyzed and simulated to show the best results. [ABSTRACT FROM AUTHOR]

In recent years the popularity of multi-hop wireless networks has been growing. Its flexible topology and abundant routing path enables many types of applications. However, the lack of a centralized controller often makes it difficult to design a reliable service in multi-hop wireless networks. While packet routing has been the center of attention for decades, recent research focuses on data discovery such as file sharing in multi-hop wireless networks. Although there are many peer-to-peer lookup (P2P-lookup) schemes for wired networks, they have inherent limitations for multi-hop wireless networks. First, a wired P2P-lookup builds a search structure on the overlay network and disregards the underlying topology. Second, the performance guarantee often relies on specific topology models such as random graphs, which do not apply to multi-hop wireless networks. Past studies on wireless P2P-lookup either combined existing solutions with known routing algorithms or proposed tree-based routing, which is prone to traffic congestion. In this paper, we present two wireless P2P-lookup schemes that strictly build a topology-dependent structure. We first propose the Ring Interval Graph Search (RIGS) that constructs a DHT only through direct connections between the nodes. We then propose the ValleyWalk, a loosely-structured scheme that requires simple local hints for query routing. Packet-level simulations showed that RIGS can find the target with near-shortest search length and ValleyWalk can find the target with near-shortest search length when there is at least 5% object replication. We also provide an analytic bound on the search length of ValleyWalk. [ABSTRACT FROM AUTHOR]

Network analysis has proved to be very useful in many social and natural sciences, and in particular Small World topologies have been exploited in many application fields. In this article, we focus on P2P file sharing applications, where spontaneous communities of users are studied and analyzed. We define a family of structures that we call "Affinity Networks" (or even Graphs) that show self-organized interest-based clusters. Empirical evidence proves that affinity networks are small worlds and shows scale-free features. The relevance of this finding is augmented with the introduction of a proactive recommendation scheme, namely DeHinter, that exploits this natural feature. The intuition behind this scheme is that a user would trust her network of "elective affinities" more than anonymous and generic suggestions made by impersonal entities. The accuracy of the recommendation is evaluated by way of a 10-fold cross validation, and a prototype has been implemented for further feedbacks from the users. [ABSTRACT FROM AUTHOR]

The transfer of large input data files in P2P computing Grids often leads to delays in Task completion times. Existing research related to this topic has been focused on the spatial grouping of Tasks, i.e. reuse of available data through data caching and data-aware scheduling. However, it tends to decrease the level of parallelism of Task execution. In this paper, this issue is addressed by integrating the BitTorrent P2P file sharing protocol, a novel Task selection scheduling algorithm, an existing online, data-aware Resource selection algorithm (similar to Storage Affinity), and caching support. These algorithms have been implemented in the Lightweight Bartering Grid middleware. The Java implementation relies exclusively on Free and Open Source data transfer software (Azureus, Apache FTP server, edtFTPj). The proposed data transfer architecture does not need Predictive Communications Ordering or an explicit deployment of an overlay network. It is also easily deployable. Our main contribution is the joint use of P2P computing and P2P file sharing technologies, enabling a highly scalable and adaptive data transfer architecture to support P2P computing. [ABSTRACT FROM AUTHOR]

Previous analytical studies of unstructured P2P resilience have assumed exponential user lifetimes and only considered age-independent neighbor replacement. In this paper, we overcome these limitations by introducing a general node-isolation model for heavy-tailed user lifetimes and arbitrary neighbor-selection algorithms. Using this model, we analyze two age-biased neighbor-selection strategies and show that they significantly improve the residual lifetimes of chosen users, which dramatically reduces the probability of user isolation and graph partitioning compared with uniform selection of neighbors. In fact, the second strategy based on random walks on age-proportional graphs demonstrates that, for lifetimes with infinite variance, the system monotonically increases its resilience as its age and size grow. Specifically, we show that the probability of isolation converges to zero as these two metrics tend to infinity. We finish the paper with simulations in finite-size graphs that demonstrate the effect of this result in practice. [ABSTRACT FROM AUTHOR]

Efficient discovery of information, based on partial knowledge, is a challenging problem faced by many large scale distributed systems. This paper presents Plexus, a peer-to-peer search protocol that provides an efficient mechanism for advertising a bit-sequence (pattern), and discovering it using any subset of its 1-bits. A pattern (e.g., Bloom filter) summarizes the properties (e.g., key-words, service description) associated with a shared object (e.g., document, service). Plexus has a partially decentralized architecture involving super- peers. It adopts a novel structured routing mechanism derived from the theory of Error Correcting Codes (ECC). Plexus achieves better resilience to peer failure by utilizing replication and redundant routing paths. Routing efficiency in Plexus scales logarithmically with the number of superpeers. The concept presented in this paper is supported with theoretical analysis, and simulation results obtained from the application of Plexus to partial keyword search utilizing the extended Golay code. [ABSTRACT FROM AUTHOR]

Abstract: The recent availability of broadband Internet access and web-based visualization techniques is paving the way for a large scale use of 3D landscape and city models in a great variety of professional and mass market services. To make such services appealing to a large audience, these 3D models must reach a sufficient level of realism and accuracy. Many solutions are now available to automatically generate 3D models of huge urban environments. Geographic information system (GIS) databases (i.e., terrain elevation grids, orthophotographs, buildings, footprint and height) provide a good basis for generating such models at affordable cost with minimum human intervention. However, the growing size of the generated representations will favor streaming over download-and-play. Moreover, the new market for virtual worlds is likely to be soon demanding interoperability. The goal of this paper is to show how solutions based on hierarchical level of detail (LOD) models and view-dependent progressive streaming can efficiently be implemented using the MPEG-4 AFX standard in peer-to-peer network architectures, solving both streaming and interoperability issues. [Copyright &y& Elsevier]