351 research outputs found

    Experimenting with Gnutella Communities

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    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 rĂ©seaux informatique ainsi que les systĂšmes distribuĂ©s peuvent ĂȘtre considĂ©rĂ©s comme des communautĂ©s oĂč les composantes - que ce soit des systĂšmes complets, des programmes ou des usagers - interagissent dans un environnement partagĂ©. Ces communautĂ©s sont dynamiques car des Ă©lĂ©ments peuvent s'y joindre ou quitter en tout temps. L'article prĂ©sente les rĂ©sultats d'une suite d'expĂ©riences et de mesures faites sur Gnutella, un systĂšme peer-to-peer Ă  grande Ă©chelle qui opĂšre sans aucun contrĂŽle centralisĂ©. Nous avons remarquĂ© qu'une grande partie des messages Ă©changĂ©s sont erronĂ©s ou redondants et que les interactions entre n?uds ne durent pas trĂšs longtemps. En particulier, des connexions durant plus d'une minute sont des phĂ©nomĂšnes rares. Les n?uds passent donc la majoritĂ© de leur temps Ă  remplacer les partenaires perdus et, contrairement Ă  l'idĂ©e rĂ©pandue que les rĂ©seaux peer-to-peer sont immenses, nous avons notĂ© que les communautĂ©s effectives Ă©taient assez limitĂ©es. Gnutella est un environnement trĂšs dynamique avec peu de stabilitĂ©. Par exemple, de 42,000 sites avec lesquels nous avons Ă©tabli une connexion, il a seulement Ă©tĂ© possible de re-communiquer de façon rĂ©guliĂšre avec 57. Dans un tel environnement, la chance joue un rĂŽle important dans la performance observĂ©e; mais nous avons Ă©laborĂ© un protocole expĂ©rimental permettant de comparer diverses options.Gnutella, peer-to-peer networks, Internet communities, distributed systems, protocols, Gnutella, rĂ©seaux peer-to-peer, communautĂ©s virtuelles, internet, systĂšmes distribuĂ©s, protocoles de tĂ©lĂ©communication

    Simulating social relations in multi-agent systems

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    Open distributed systems are comprised of a large number of heterogeneous nodes with disparate requirements and objectives, a number of which may not conform to the system specification. This thesis argues that activity in such systems can be regulated by using distributed mechanisms inspired by social science theories regarding similarity /kinship, trust, reputation, recommendation and economics. This makes it possible to create scalable and robust agent societies which can adapt to overcome structural impediments and provide inherent defence against malicious and incompetent action, without detriment to system functionality and performance. In particular this thesis describes: ‱ an agent based simulation and animation platform (PreSage), which offers the agent developer and society designer a suite of powerful tools for creating, simulating and visualising agent societies from both a local and global perspective. ‱ a social information dissemination system (SID) based on principles of self organisation which personalises recommendation and directs information dissemination. ‱ a computational socio-cognitive and economic framework (CScEF) which integrates and extends socio-cognitive theories of trust, reputation and recommendation with basic economic theory. ‱ results from two simulation studies investigating the performance of SID and the CScEF. The results show the production of a generic, reusable and scalable platform for developing and animating agent societies, and its contribution to the community as an open source tool. Secondly specific results, regarding the application of SID and CScEF, show that revealing outcomes of using socio-technical mechanisms to condition agent interactions can be demonstrated and identified by using Presage.Open Acces

    CHORUS Deliverable 2.1: State of the Art on Multimedia Search Engines

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    Based on the information provided by European projects and national initiatives related to multimedia search as well as domains experts that participated in the CHORUS Think-thanks and workshops, this document reports on the state of the art related to multimedia content search from, a technical, and socio-economic perspective. The technical perspective includes an up to date view on content based indexing and retrieval technologies, multimedia search in the context of mobile devices and peer-to-peer networks, and an overview of current evaluation and benchmark inititiatives to measure the performance of multimedia search engines. From a socio-economic perspective we inventorize the impact and legal consequences of these technical advances and point out future directions of research

    Sharing Economy Business Models : Addressing the design-implementation gap

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    Despite sharing being a long-practiced form of consumption, the concept ‘sharing economy’ has emerged only recently. New business models have proliferated, utilising technology to reduce transaction costs and facilitate shared access. Societal actors have taken interest in the sharing economy, to reduce resource consumption, foster social cohesion, and support the economy. However, sharing economy business models facilitate a wide array of consumption practices, including sharing, renting, borrowing, lending, bartering, swapping, trading, exchanging, gifting, buying second-hand, and even buying new goods. Past academic research and media attention tend to focus on unicorns such as Airbnb and Uber. There is greater need to explore the diverse permutations of business models within the sharing economy, especially considering sustainability.However, a gap exists between the design and successful implementation of sharing economy business models. This research aims to advance and structure knowledge about the sharing economy and sustainable business models, by using business modelling methods to study the design and implementation of sharing economy business models. Inspired by design science, this research engages in prescriptive theory-building and design- oriented research to construct and evaluate design artefacts. Incorporating data materials from people, documents, and literature, the research strategies of grounded theory and desk research are utilised to support methods for data collection and data analysis.The research proposes a prescriptive definition of the sharing economy as a socio-economic system that leverages technology to mediate two-sided markets, which facilitate temporary access to goods that are under- utilised, tangible, and rivalrous. From this, four design principles guide the formation of the sharing economy business model framework, which capture three value dimensions, sixteen business model attributes, and eighty- nine configuration options. This research proposes a coherent design theory to support the conceptualisation of sharing economy business models for sustainability.Additional artefacts are developed to support the successful implementation of these business models. First, business model patterns provide the justificatory knowledge to select relevant business model attributes in specific contexts. Then, a systematic framework measures the social impact of sharing platforms across four aspects – trust, empowerment, social justice, and inclusivity. Finally, organisational response strategies to COVID-19 are established in the sharing economy.The primary contribution of this research is conceptual, with additional modest methodological and empirical contributions. Furthermore, the artefacts are intended to be useful for research and practice, including scholars, entrepreneurs, managers, policymakers, investors, users, and concerned citizens

    P2PCompute - A Peer-to-Peer Computing Model

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    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\u27 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
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