743 research outputs found

    On the Impact of Practical P2P Incentive Mechanisms on User Behavior

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    In this paper we report on the results of a large-scale measurement study of two popular peer-topeer systems, namely BitTorrent and eMule, that use practical and lightweight incentive mechanisms to encourage cooperation between users. We focus on identifying the strategic behavior of users in response to those incentive mechanisms. Our results illustrate a gap between what system designers and researchers expect from users in reaction to an incentive mechanism, and how users react to those incentives. In particular, we observe that the majority of BitTorrent users appear to cooperate well, despite the existence of known ways to tamper with the incentive mechanism, users engaging in behavior that could be regarded as cheating comprised only around 10% of BitTorrent’s population. That is, although we know that users can easily cheat, they actually do not currently appear to cheat at a large enough scale. In the eMule system, we identify several distinct classes of users based on their behavior. A large fraction of users appears to perceive cooperation as a good strategy, and openly share all the files they obtained. Other users engage in more subtle strategic choices, by actively optimizing the number and types of files they share in order to improve their standing in eMule’s waiting queues; they tend to remove files for which downloading is complete and keep a limited total volume of files shared

    On the Impact of Practical P2P Incentive Mechanisms on User Behavior

    Get PDF
    In this paper we report on the results of a large-scale measurement study of two popular peer-topeer systems, namely BitTorrent and eMule, that use practical and lightweight incentive mechanisms to encourage cooperation between users. We focus on identifying the strategic behavior of users in response to those incentive mechanisms. Our results illustrate a gap between what system designers and researchers expect from users in reaction to an incentive mechanism, and how users react to those incentives. In particular, we observe that the majority of BitTorrent users appear to cooperate well, despite the existence of known ways to tamper with the incentive mechanism, users engaging in behavior that could be regarded as cheating comprised only around 10% of BitTorrent’s population. That is, although we know that users can easily cheat, they actually do not currently appear to cheat at a large enough scale. In the eMule system, we identify several distinct classes of users based on their behavior. A large fraction of users appears to perceive cooperation as a good strategy, and openly share all the files they obtained. Other users engage in more subtle strategic choices, by actively optimizing the number and types of files they share in order to improve their standing in eMule’s waiting queues; they tend to remove files for which downloading is complete and keep a limited total volume of files shared

    Confidential Data-Outsourcing and Self-Optimizing P2P-Networks: Coping with the Challenges of Multi-Party Systems

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    This work addresses the inherent lack of control and trust in Multi-Party Systems at the examples of the Database-as-a-Service (DaaS) scenario and public Distributed Hash Tables (DHTs). In the DaaS field, it is shown how confidential information in a database can be protected while still allowing the external storage provider to process incoming queries. For public DHTs, it is shown how these highly dynamic systems can be managed by facilitating monitoring, simulation, and self-adaptation

    Contributions to Desktop Grid Computing : From High Throughput Computing to Data-Intensive Sciences on Hybrid Distributed Computing Infrastructures

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    Since the mid 90’s, Desktop Grid Computing - i.e the idea of using a large number of remote PCs distributed on the Internet to execute large parallel applications - has proved to be an efficient paradigm to provide a large computational power at the fraction of the cost of a dedicated computing infrastructure.This document presents my contributions over the last decade to broaden the scope of Desktop Grid Computing. My research has followed three different directions. The first direction has established new methods to observe and characterize Desktop Grid resources and developed experimental platforms to test and validate our approach in conditions close to reality. The second line of research has focused on integrating Desk- top Grids in e-science Grid infrastructure (e.g. EGI), which requires to address many challenges such as security, scheduling, quality of service, and more. The third direction has investigated how to support large-scale data management and data intensive applica- tions on such infrastructures, including support for the new and emerging data-oriented programming models.This manuscript not only reports on the scientific achievements and the technologies developed to support our objectives, but also on the international collaborations and projects I have been involved in, as well as the scientific mentoring which motivates my candidature for the Habilitation `a Diriger les Recherches

    Towards Scalable, Accurate, and Usable Simulations of Distributed Applications and Systems

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    The study of parallel and distributed applications and platforms, whether in the cluster, grid, peer-to-peer, volunteer, or cloud computing domain, often mandates empirical evaluation of proposed algorithm and system solutions via simulation. Unlike direct experimentation via an application deployment on a real-world testbed, simulation enables fully repeatable and configurable experiments that can often be conducted quickly for arbitrary hypothetical scenarios. In spite of these promises, current simulation practice is often not conducive to obtaining scientifically sound results. State-of-the-art simulators are often not validated and their accuracy is unknown. Furthermore, due to the lack of accepted simulation frameworks and of transparent simulation methodologies, published simulation results are rarely reproducible. We highlight recent advances made in the context of the SimGrid simulation framework in a view to addressing this predicament across the aforementioned domains. These advances, which pertain both to science and engineering, together lead to unprecedented combinations of simulation accuracy and scalability, allowing the user to trade off one for the other. They also enhance simulation usability and reusability so as to promote an Open Science approach for simulation-based research in the field.L'Ă©tude de systĂšmes et applications parallĂšles et distribuĂ©s, qu'il s'agisse de clusters, de grilles, de systĂšmes pair-Ă -pair de volunteer computing, ou de cloud, demandent souvent l'Ă©valuation empirique par simulation des algorithmes et solutions proposĂ©s. Contrairement Ă  l'expĂ©rimentation directe par dĂ©ploiement d'applications sur des plates-formes rĂ©elles, la simulation permet des expĂ©riences reproductibles pouvant ĂȘtre menĂ©e rapidement sur n'importe quel scĂ©nario hypothĂ©tique. MalgrĂ© ces avantages thĂ©oriques, les pratiques actuelles en matiĂšre de simulation ne permettent souvent pas d'obtenir des rĂ©sultats scientifiquement Ă©prouvĂ©s. Les simulateurs classiques sont trop souvent validĂ©s et leur rĂ©alisme n'est pas dĂ©montrĂ©. De plus, le manque d'environnements de simulation communĂ©ment acceptĂ©s et de mĂ©thodologies classiques de simulation font que les rĂ©sultats publiĂ©s grĂące Ă  cette approche sont rarement reproductibles par la communautĂ©. Nous prĂ©sentons dans cet article les avancĂ©es rĂ©centes dans le contexte de l'environnement SimGrid pour rĂ©pondre Ă  ces difficultĂ©s. Ces avancĂ©es, comprenant Ă  la fois des aspects techniques et scientifiques, rendent possible une combinaison inĂ©galĂ©e de rĂ©alisme et prĂ©cision de simulation et d'extensibilitĂ©. Cela permet aux utilisateurs de choisir le grain des modĂšles utilisĂ©s pour ses simulations en fonction de ses besoins de rĂ©alisme et d'extensibilitĂ©. Les travaux prĂ©sentĂ©s ici amĂ©liorent Ă©galement l'utilisabilitĂ© et la rĂ©utilisabilitĂ© de façon Ă  promouvoir l'approche d'Open Science pour les recherches basĂ©es sur la simulation dans notre domaine

    NABOH system: Gathering intelligence from traffic patterns

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    Network traffic anomalies are important indicators of problematic traffic over a network. Network activity has patterns associated with it depending on the applications running on the local hosts connected to the network. There are traffic parameters into which network traffic of a local host can be divided: bandwidth usage, number of remote hosts that a local host is connecting to and vice versa, and number of ports used by the local host. This thesis develops a system for detecting and profiling network anomalies by analyzing traffic parameters using intelligent computational techniques. The developed system gathers intelligence by examining only the headers of IP packets. Thus the system is referred to as NABOH (Network Anomalies Based On Headers)

    Law and the “Sharing Economy”

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    The rapid expansion of sharing economy platforms such as Airbnb and Uber has generated enormous controversy. This book brings legal and interdisciplinary perspectives to the labour, market and technology and other regulatory challenges that arise from this phenomenon that has taken the world by storm

    Resource management for next generation multi-service mobile network

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    Developing a security mechanism for software agents

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    Thesis (Master)--Izmir Institute of Technology, Computer Engineering, Izmir, 2006Includes bibliographical references (leaves: 73-76)Text in English; Abstract: Turkish and Englishx 76 leavesThis thesis proposes a message security solution on multi-agent systems. A general security analysis based on properties of software agents is presented along with an overview of security measures applicable to multi-agent systems. A security design and implementation has been developed to protect communication among agents. And this implementation scheme has been applied to Seagent, a semantic web enabled multi-agent framework. Hence, a set of agent security mechanisms have been adapted for Seagent and have been implemented for message confidentiality, integrity, authentication and nonrepudiation. Then these mechanisms have been tested for communication performance on Seagent
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