Experimenting with Gnutella Communities

Computer networks and distributed systems in general may be regarded as communities where the individual components, be they entire systems, application software or users, interact in a shared environment. Such communities dynamically evolve with components or nodes joning and leaving the system. Their own individual activities affect the community's behaviour and vice-versa. This paper discusses various experiments undertaken to investigate the behaviour of a real system, the Gnutella network, which represents such a community. Gnutella is a distributed Peer-to-Peer data-sharing system without any central control. It turns out that most interactions between nodes do not last long and much of their activity is devoted to finding appropriate partners in the network. Good connections lasting longer appear only as rare events. For example, out of 42,000 connections only 57 hosts were found to available on a regular basis. This means that, in contrast to the common belief that this kind of peer-to-peer networks or sub-communities are always large, they are actually quite small. However, those sub-communities examplify very dynamic behaviour because their actual composition can change very quickly. The experimental results presented have been obtained from a Java implementation of Gnutella running in the open Internet environment, and thus in unknown and quickly changing network structures heavily dependent on chance. Les réseaux informatique ainsi que les systèmes distribués peuvent être considérés comme des communautés où les composantes - que ce soit des systèmes complets, des programmes ou des usagers - interagissent dans un environnement partagé. Ces communautés sont dynamiques car des éléments peuvent s'y joindre ou quitter en tout temps. L'article présente les résultats d'une suite d'expériences et de mesures faites sur Gnutella, un système peer-to-peer à grande échelle qui opère sans aucun contrôle centralisé. Nous avons remarqué qu'une grande partie des messages échangés sont erronés ou redondants et que les interactions entre n?uds ne durent pas très longtemps. En particulier, des connexions durant plus d'une minute sont des phénomènes rares. Les n?uds passent donc la majorité de leur temps à remplacer les partenaires perdus et, contrairement à l'idée répandue que les réseaux peer-to-peer sont immenses, nous avons noté que les communautés effectives étaient assez limitées. Gnutella est un environnement très dynamique avec peu de stabilité. Par exemple, de 42,000 sites avec lesquels nous avons établi une connexion, il a seulement été possible de re-communiquer de façon régulière avec 57. Dans un tel environnement, la chance joue un rôle important dans la performance observée; mais nous avons élaboré un protocole expérimental permettant de comparer diverses options.Gnutella, peer-to-peer networks, Internet communities, distributed systems, protocols, Gnutella, réseaux peer-to-peer, communautés virtuelles, internet, systèmes distribués, protocoles de télécommunication

CLOSER: A Collaborative Locality-aware Overlay SERvice

Current Peer-to-Peer (P2P) file sharing systems make use of a considerable percentage of Internet Service Providers (ISPs) bandwidth. This paper presents the Collaborative Locality-aware Overlay SERvice (CLOSER), an architecture that aims at lessening the usage of expensive international links by exploiting traffic locality (i.e., a resource is downloaded from the inside of the ISP whenever possible). The paper proves the effectiveness of CLOSER by analysis and simulation, also comparing this architecture with existing solutions for traffic locality in P2P systems. While savings on international links can be attractive for ISPs, it is necessary to offer some features that can be of interest for users to favor a wide adoption of the application. For this reason, CLOSER also introduces a privacy module that may arouse the users' interest and encourage them to switch to the new architectur

Semantic social routing in Gnutella

The objective of this project is to improve the performance of the Gnutella peer-to-peer protocol (version 0.4) by introducing a semantic-social routing model and several categories of interest. The Gnutella protocol requires peers to broadcast messages to their neighbours when they search files. The message passing generates a lot of traffic in the network, which degrades the quality of service. We propose using social networks to optimize the speed of search and to improve the quality of service in a Gnutella based peer-to-peer environment. Each peer creates and updates a “friends list” from its past experience, for each category of interest. Once peers generate their friends lists, they use these lists to semantically route queries in the network. Search messages in a given category are mainly sent to “friends” who have been useful in the past in finding files in the same category. This helps to reduce the search time and to decrease the network traffic by minimizing the number of messages circulating in the system as compared to standard Gnutella. This project will demonstrate by simulating a peer-to-peer type of environment with the JADE multi-agent system platform that by learning other peers’ interests, building and exploiting their social networks (friends lists) to route queries semantically, peers can get more relevant resources faster and with less traffic generated, i.e. that the performance of the Gnutella system can be improved

Reliable and Scalable Addressing Scheme for Data Distribution

A central problem faced in distributed data storage and in peer to peer applications is the efficient location of the node where the requested data is present. Currently popular peer to peer protocols such as Chord and Gnutella require enormous overhead. In Chord protocol data needs to be moved back and forth in order to stabilize the network and in Gnutella the requests flood the network. The above problems call for an efficient and reliable addressing scheme. The protocol proposed in this thesis (CHORELLA) can accommodate a maximum of 220 nodes in the network. It takes just one hop to find any file in the network and in case of node failures, it may take a maximum of as many hops as the number of mirrors or the replication rate in the network. The files are evenly distributed among the nodes using SHA-1 hashing function.Computer Science Departmen

Reputation-based Cooperation in the Clouds

The popularity of the cloud computing paradigm is opening new opportunities for collaborative computing. In this paper we tackle a fundamental problem in open-ended cloud-based distributed comput- ing platforms, i.e., the quest for potential collaborators. We assume that cloud participants are willing to share their computational resources for shared distributed computing problems, but they are not willing to dis- closure the details of their resources. Lacking such information, we advo- cate to rely on reputation scores obtained by evaluating the interactions among participants. More specifically, we propose a methodology to as- sess, at design time, the impact of different (reputation-based) collabo- rator selection strategies on the system performance. The evaluation is performed through statistical analysis on a volunteer cloud simulator

Simulating peer-to-peer networks

Peer-to-Peer (P2P) systems are emerging as a new form of distributed computing with a strong emphasis on self-organization, decentralization, and autonomy of the participating nodes. The characteristics of self-organization, autonomy, and decentralization allow for highly adaptive, robust, and scalable networks, making P2P an increasingly interesting way to design distributed systems. Since the deployment of P2P systems involves significant resources, e.g., hundreds of hosts and users, it is often not possible to run realistic tests prior to the rollout of the system. Consequently, simulation is the only realistic approach for testing or predicting the behavior of large P2P networks. However, the majority of the existing simulators tend to provide limited flexibility in simulating the details of the users, application, protocol, and physical network. In this research, the impact of user behavior, protocol, and physical network characteristic on the overall P2P system are being observed. The aim is to investigate the importance of simulating P2P systems in such detail

Motivational visualization for resources-sharing online communities

As online applications such as online newsgroups, internet game-rooms, online chat-rooms, and peer-to-peer (P2P) resources-sharing systems become popular, online community visualization became a hot research topic. Different forms and metaphors of visualizations focused on various aspects of online communities have been proposed. In this thesis, I propose one prototype of online community visualization which is designed to motivate user contributions in various aspects and stimulate users to participate in the online community more actively. The uneven participation is a well known problem in human society; according to the 80-20 rule, 20% of the people make 80% of contributions, for example, 20% of the employees in a company do 80% of the work. This problem exits in all kinds of online communities, e.g. newsgroups, chat-rooms, but it is particularly crucial for P2P online resources-sharing communities. Such communities do not have a central server and rely solely on the peers not just to provide contributions, but also to ensure the infrastructure. Large P2P file-sharing communities like KaZaA and Limewire can provide the redundancy of peers and resources needed to support the infrastructure and availability of resources. However, when an online community is small, for example, the students in a class, a research group, a department, or a school, the problem of lack of users it is hard to reach a “critical mass” of user participation, leading to poor service and resource availability, which reduces users’ interest in participating in the system. To attract users and motivate them to make more contributions into an online resources-sharing community, I propose to use motivational visualization of the community and the contributions of its members. The motivational effect of the visualization is grounded on two theories in social psychology which explain how individuals align their behaviour with each other and with their group (community). In this thesis, I discuss three stages in the design of the visualization and the subsequent redesigns following results from evaluation and user feedback