File-sharing Networks Research Articles

Query-Trail-Mediated Cooperative Behaviors of Peers in Unstructured P2P File Sharing Networks

We propose two types of autonomic and distributed cooperative behaviors of peers for peer-to-peer (P2P) file-sharing networks. Cooperative behaviors of peers are mediated by query trails, and allows the exploration of better trade-off points between file search and storage load balancing performance. Query trails represent previous successful search paths and indicate which peers contributed to previous file searches and were at the same time exposed to the storage load. The first type of cooperative behavior is to determine the locations of replicas of files through the medium of query trails. Placement of replicas of files on strong query trails contributes to improvement of search performance, but a heavy load is generated due to writing files in storage to peers on the strong query trails. Therefore, we attempt to achieve storage load balancing between peers, while avoiding significant degradation of the search performance by creating replicas of files in peers adjacent to peers on strong query trails. The second type of cooperative behavior is to determine whether peers provide requested files through the medium of query trails. Provision of files by peers holding requested files on strong query trails contributes to better search performance, but such provision of files generates a heavy load for reading files from storage to peers on the strong query trails. Therefore, we attempt to achieve storage load balancing while making only small sacrifices in search performance by having peers on strong query trails refuse to provide files. Simulation results show that the first type of cooperative behavior provides equal or improved ability to explore trade-off points between storage load balancing and search performance in a static and nearly homogeneous P2P environment, without the need for fine tuning parameter values, compared to replication methods that require fine tuning of their parameters values. In addition, the combination of the second type and the first type of cooperative behavior yields better storage load balancing performance with little degradation of search performance. Moreover, even in a dynamic and heterogeneous P2P environment, the two types of cooperative behaviors yield good ability to explore trade-off points between storage load balancing and search performance.

Turning Piracy into Profits: a Theoretical Investigation

We analyse how the presence of a (private, small-scale) file-sharing community affects the profitability of producers of digital goods within a spatial duopoly model à la Hotelling (1929). Consumers can download pirated content by joining this file-sharing network. To gain access to the community, consumers have to buy and share a digital good with other members. We show that firms benefit from piracy in emerging markets, that is, markets that are not fully covered. The activity of file-sharing, in fact, allows firms to reach a larger share of customers who otherwise would not buy at all. This effect is missing in mature and widespread markets where firms prefer to be protected from piracy. Our results provide a rationale for the observation that in emerging countries, companies are unlikely to take a firm stance against piracy.

Competition against peer-to-peer networks

In this paper, we consider the competition of a monopolistic provider of information products against a peer-to-peer file-sharing network that offers illegal versions of the products. We focus on the role of direct externalities caused by the P2P file-sharing technology rather than the indirect consumption externalities studied previously in the literature. In our model the market structure is endogenous and we characterize three possible scenarios where the firm uses monopoly pricing, network-deterring pricing, and network-accommodating pricing, respectively. We make a full comparative-static analysis of prices, quantities, profits, consumer surplus and total surplus for each of the scenarios as well as a comparison across scenarios. We show that in the case of network-accommodating pricing, the firm sets a higher price when facing a lower generic cost factor of downloading. Furthermore, in all scenarios, profits for the firm unambiguously decrease when the generic cost factor of downloading declines; total welfare unambiguously increases, however, a result that has implications for intellectual property rights enforcement policy.

Interacting branching processes and linear file-sharing networks

File-sharing networks are distributed systems used to disseminate files among nodes of a communication network. The general simple principle of these systems is that once a node has retrieved a file, it may become a server for this file. In this paper, the capacity of these networks is analyzed with a stochastic model when there is a constant flow of incoming requests for a given file. It is shown that the problem can be solved by analyzing the asymptotic behavior of a class of interacting branching processes. Several results of independent interest concerning these branching processes are derived and then used to study the file-sharing systems.

Interacting branching processes and linear file-sharing networks

File-sharing networks are distributed systems used to disseminate files among nodes of a communication network. The general simple principle of these systems is that once a node has retrieved a file, it may become a server for this file. In this paper, the capacity of these networks is analyzed with a stochastic model when there is a constant flow of incoming requests for a given file. It is shown that the problem can be solved by analyzing the asymptotic behavior of a class of interacting branching processes. Several results of independent interest concerning these branching processes are derived and then used to study the file-sharing systems.

A free-rider aware reputation system for peer-to-peer file-sharing networks

Recently, Peer-to-Peer (P2P) networks have widely been used to file-sharing applications due to their decentralized architecture and reliability. The popularization of P2P networks also provides peers with ulterior motive an ideal environment to spread malicious files. In the past, many reputation systems have been proposed to differentiate malicious peers and to stop malicious file spreading. However, these reputation systems do not concern with reducing free riders in P2P networks. Free riders are peers who just download files but do not share anything to other peers. They significantly destroy the philosophy of P2P file-sharing networks. In this paper, we propose a free-rider aware reputation system for P2P file-sharing networks. Indeed, our reputation system can degrade the willing of free riders. Compared to most existing reputation systems, our reputation system provides an easy way to reduce malicious file spreading and free riding.

Access Load Balancing with Analogy to Thermal Diffusion for Dynamic P2P File-Sharing Environments

SUMMARY In this paper, we propose a file replication method to achieve load balancing in terms of write access to storage device (“write storage access load balancing” for short) in unstructured peer-to-peer (P2P) file-sharing networks in which the popularity trend of queried files varies dynamically. The proposed method uses a write storage access ratio as a load balance index value in order to stabilize dynamic P2P file-sharing environments adaptively. In the proposed method, each peer autonomously controls the file replication ratio, which is defined as a probability to create the replica of the file in order to uniform write storage access loads in the similar way to thermal diffusion phenomena. Theoretical analysis results show that the behavior of the proposed method actually has an analogy to a thermal diffusion equation. In addition, simulation results reveal that the proposed method has an ability to realize write storage access load balancing in the dynamic P2P file-sharing environments.

Piracy-Minimizing Non-Linear Pricing Of Digital Goods With Unknown Demand And Price-Based Coordination In 'Open Cooperative' Peer-To-Peer Networks

Although the number of “legal” online filesharing networks has increased, Digital Piracy has become more pervasisve and affects several industries such as new/information, entertainment, education, sports, etc. The main objectives of this article are a) to develop pricing schemes (for digital content) that reduce the information producers’ losses from copyright infringement while maximizing social welfare, b) analyze how the present mispricing of internet access contributes to illegal online file-sharing.

Piracy-Minimizing Non-Linear Pricing of Differentiated Digital Goods in Client-Server Networks, and Distribution Choices Under Constrained Transferable Utility

Although the number of “legal” online filesharing networks has increased, Digital Piracy has become more pervasisve and affects several industries such as new/information, entertainment, education, sports, etc. The main objectives of this article are a) to develop pricing schemes (for digital content) that reduce the information producers’ losses from copyright infringement while maximizing social welfare, b) show how the configuration of networks affects propensity for Digital Piracy and pricing of digital content; c) analyze how the present mispricing of internet access contributes to illegal online file-sharing.

A Survey of Critical Issues in Digital Piracy and the Pricing of Digital Content

Although the number of “legal” online filesharing networks has increased, Digital Piracy has become more pervasisve and affects several industries such as new/information, entertainment, education, sports, etc. The main objectives of this article are: a) to critique the major existing literature on the pricing of digital content; b) show how the configuration of networks affects propensity for Digital Piracy and pricing of digital content.

Piracy on the Internet: Accomodate it or Fight it? A Dynamic Approach

This paper uses a dynamic stochastic model to solve for the optimal pricing policy of the music recording companies in the presence of P2P file-sharing networks eroding their CD sales. We employ a policy iteration algorithm on a discretized state space to numerically compute the optimal price policy. The realistically calibrated model reflects the real-world figures we observe and provides estimates of figures we can not observe, such as changes in total welfare. The results suggest that, thanks to the existence of P2P networks, total welfare in 2008 in the U.S. is about $25.6 billion more per annum than in 1999 before P2P was introduced. Moreover, the results predict that the current trend of decreasing CD sales will continue until around the year 2020 when it will stabilize at around 231.2 million copies per year, comparing to the industry all-time high of 938.9 million in 1999. The comparative static analysis shows that full enforcement of intellectual property rights, although helpful for the industrial profit, may have adverse effect on total welfare.

Efficient and scalable search on scale-free P2P networks

Unstructured peer-to-peer (P2P) systems (e.g. Gnutella) are characterized by uneven distributions of node connectivity and file sharing. The existence of “hub” nodes that have a large number of connections and “generous” nodes that share many files significantly influences performance of information search over P2P file-sharing networks. In this paper, we present a novel Scalable Peer-to-Peer Search (SP2PS) method with low maintenance overhead for resource discovery in scale-free P2P networks. Different from existing search methods which employ one heuristic to direct searches, SP2PS achieves better performance by considering both of the number of shared files and the connectivity of each neighbouring node. SP2PS enables peer nodes to forward queries to the neighbours that are more likely to have the requested files and also can help in finding the requested files in the future hops. The proposed method has been simulated in different power-law networks with different forwarding degrees and distances. From our analytic and simulation results, SP2PS achieves better performance when compared to other related methods.

Recovering Fair Use

Recovering Fair Use

Modeling of virus propagation in peer-to-peer file-sharing networks

To counter the attacks of virus in P2P file-sharing networks,the model of virus propagation in P2P networks was proposed based on deep analysis on the features of file sharing and virus propagation.In order to examine the effect of different parameters in this model,large scale simulating experiments were carried out.The fact that different parameters have varied effect on virus propagation shows that virus propagation can be throttled by controlling those key parameters.

Stability and Efficiency of Unstructured File Sharing Networks

We propose two unstructured file sharing games, unilateral and bilateral unstructured file sharing games, to study the interaction among self-interested players (users) of unstructured P2P file sharing applications. In a unilateral unstructured file sharing game, players compete for network resources (link bandwidth) by opening multiple connections to each other on multiple paths so as to maximize their individual benefits. A player always allows other players to connect to itself. Multiple concurrent connections are allowed on any path between a pair of players. Per-connection throughput is determined by the transport protocol implemented by users' computers. In a bilateral unstructured file sharing game, users adopt a Tit-for-Tat strategy, under which an active connection between two players is set up only when they both find it beneficial. Two players can set up at most one connection between themselves and bottlenecks occur only at upstream access links in a star network. For both games, we prove the existence of an equilibrium, quantify the efficiency losses of equilibria, and demonstrate the dynamic stability of equilibria in best-response or better-response dynamic game playing processes.

Reconfiguring Television for a Networked, Produsage Context

The rise of user-led content creation and distribution, or produsage, is by now well recognised. User-produced content is providing a well-needed corrective to industrial journalism; user-produced creative work has become a regular component of the standard media diet for many users; and user-led distribution of content through file-sharing networks is now an important means of accessing content, and is cautiously being explored as a means of distribution by mainstream media producers. Such phenomena are beginning to affect the television industry. On the one hand, the user-led distribution of television programming now enables producers to bypass traditional distribution channels altogether; on the other, traditional television channels are already anticipating such moves through an increase in live content and event television. There is also a contrary movement of user-produced material further into the mainstream of the mediasphere. This article outlines a number of the operational models now available to players in the television industry: enlisting file-sharers in the direct distribution of TV shows to audiences; moving further towards a focus on live event television; and embracing user creativity in pursuit of produsage-based television models. It examines these options against a context of continuing convergence and change in the content industries.

Illegal Online Filesharing, Risk And Optimal Sanctions

Illegal online filesharing is clearly a major problem that involves various unresolved policy, technological and economics problems. Despite very well publicized investigations, lawsuits and prosecutions of ISPs and individuals, illegal filesharing continues in networks; and some companies have even introduced fourth-generation filesharing systems that are based on 'anonymity and streaming of data. This article is entirely theoretical and: a) analyzes risk and perceptions of risk by and among participants in illegal online filesharing networks; b) expands the literature by introducing conditions under which the illegal filesharing perpetrators will continue illegal conduct, c) introduces the criteria for optimal sanctions. Theories of risks and perceptions of risk in illegal filesharing can help in allocation of resources to investigation and enforcement efforts, and in development of effective penalties and sanctions.

Piracy on File-sharing Networks: Strategies for Recording Companies

In this article, we study the impact on piracy of selling music as downloadable files and the strategies that recording companies should adopt to increase profits. We find that total music sales and profits of firm (recording company) are higher, and total piracy (demand on file-sharing networks) is lower when the firm sells a downloadable version of a music track. We also look at the firm's optimal level of digital rights management (DRM) protection. We found that revenue decreases with increased protection. It is therefore optimal for the firm not to employ any DRM protection in the absence of network externality (NE). Listening to music or watching videos protected by DRM is cumbersome to users because they have to download license files and there are restrictions on the number of times the file can be copied and on the type of devices that can play the file. As a result, DRM protection is a disutility to the legal consumer and the firm must charge lower prices with more DRM protection. When NE is high and a nominal search cost is above a certain threshold, then non-zero protection becomes optimal.

Amazon Noir

Amazon Noir

Special Issue: Recent Advances in Peer‐to‐Peer Systems and Security

Peer-to-peer systems have revolutionized the way we store 1, 2, disseminate 3, 4 and share 5, 6 content. In recent years, researchers have examined numerous aspects of these innovative architectures and proposed numerous protocols and applications. While peer-to-peer research has impacted a number of areas, including theory, networking, databases and distributed systems, recent work has focused more on the issues of practical, deployable systems, measurements, and issues of security and privacy in peer-to-peer applications. This issue brings together recent work on several projects focused on building robust, practical peer-to-peer systems. The work described has also been presented at the 5th international workshop on peer-to-peer systems (IPTPS 2006), an annual forum for researchers and practitioners of large distributed systems, held in Santa Barbara, California, and attended by more than 80 participants. The goal of the workshop was to examine peer-to-peer technologies, applications and systems, and to identify key research issues and challenges that lie ahead. In the context of this workshop, peer-to-peer systems were characterized as being decentralized, self-organizing distributed systems, in which all or most communication is symmetric. This issue includes five papers, two of which 7, 8 present novel approaches to enhance the efficiency of current file-sharing networks, while the other three 9-11 examine security-related issues including reputations, incentives and misbehaving users. In the first paper, Epema et al. 7 propose Tribler, a new content-sharing protocol that leverages social relationships to enhance performance. While Tribler leverages BitTorrent's downloading mechanism, it is primarily a social network, where users obtain persistent, long-term identities, and self-organize according to their preferences and operational history. By leveraging shared interests, Tribler encourages users to behave altruistically, and shows that with willing helpers, downloaders can dramatically reduce their download latencies. The second paper 8 proposes the novel application of a probabilistic counting algorithm to hybrid search. To estimate whether a file is popular, the authors propose that super-peers count its occurrence by applying the Flajolet–Martin algorithm, where each member of a set flips a fair coin up to N times, and counts the number of heads seen before the first tail. The maximum value from all members is an approximate count of the set size. The remaining papers discuss issues closely related to reputations and user behavior. In the first paper, Swamynathan et al. 11 examine one of the challenges of applying reputation systems to peer-to-peer networks, that of short session histories. She proposes a proactive reputation scheme that allows peers to actively probe and test unknown peers with sample requests, all while making the probes indistinguishable from normal transactional requests and remaining anonymous. Second, Lian et al. 9 show using measurements that in the presence of colluding users, global reputation systems such as EigenTrust can produce non-ideal results. They propose instead a multi-trust reputation approach that bridges the gap between personal trust and global trust, and shows how it addresses the issues of collusion behavior found in current peer-to-peer networks. Finally, Liogkas et al. 10 explore the effectiveness of incentive and enforcement mechanisms in the popular BitTorrent network by implementing and evaluating three different exploits. They evaluate their strategies on both private and public BitTorrent networks, and present some surprising results.