This paper attempts to unpack a few of the vast array of assumptions implicit in how "the technology" known as Napster was understood by several of its key constituencies. Our approach examines discourse about Napster in several areas - legal, economic, social, and cultural. This approach enables us to understand "the technology" as an ongoing encounter, rather than the accomplishment of any one inventor, team of inventors, dominant institution, or rule of law. We do not offer proscriptive advice. While there is value in other research that has tried to determine the "impact of Napster on" a particular market or industry, we argue that a multidimensional understanding is necessary both as a foundation for such research as well as in its own right. In only the past four years, dominant interpretations of Napster have not only emerged, but also have been inscribed into laws, business plans, and purchasing decisions, in effect, determining what "tools" - precedents, myths, data sets, prior objects, capabilities - will be available in the future. Our paper tries to show how and why certain (subjective) significations increasingly have taken on the status of truth, while other (equally subjective) discourses have been pushed farther and farther out to the fringes

Recently, researchers have introduced the notion of super-peers to improve signaling efficiency as well as lookup performance of peer-to-peer (P2P) systems. In a separate development, recent works on applications of mobile ad hoc networks (MANET) have seen several proposals on utilizing mobile fleets such as city buses to deploy a mobile backbone infrastructure for communication and Internet access in a metropolitan environment. This paper further explores the possibility of deploying P2P applications such as content sharing and distributed computing, over this mobile backbone infrastructure. Specifically, we study how city buses may be deployed as a mobile system of super-peers. We discuss the main motivations behind our proposal, and outline in detail the design of a super-peer based structured P2P system using a fleet of city buses. / Singapore-MIT Alliance (SMA)

We present WASP (World-friendly Active packets for ephemeral State Processing), a novel active networks architecture that enables ephemeral storage of information on routers in order to ease distributed application synchronisation and co-operation. We aimed at a design compatible with modern routers hardware and with network operators' goals. Our solution has to scale with the number of interfaces of the device and to support throughput of several Gbps. Throughout this thesis we searched for the best trade-off between features (platform exibility) and guarantees (platform safety), with as little performance sacri ce as possible. We picked the Ephemeral State Processing (ESP) router, developed by K. Calvert's team at University of Kentucky, as a starting point and extended it with our own virtual processor (VPU) to offer higher exibility to the network programmer. The VPU is a minimalist bytecode interpreter that manipulates the content of the "ephemeral state store" of the router according to a microprogram present in packets. It ultimately allows the microprogram to drop or forward the packet on any router, acting as remotely programmable filters around unmodified IP routing cores. We developed two implementations of WASP: a "reference" module for the Linux kernel, and, based on that prototype experience, a WASP filter application for the IXP2400 network processor that proves feasibility of our platform at higher speed. We extensively tested those two implementations against their ESP counterpart in order to estimate the overhead of our approach. High speed tests on the IXP were also performed to ensure WASP's robustness, and were actually rich in lessons for future development on programmable network devices. The nature of WASP makes it a platform of choice to detect properties of the network along a given path. Thanks to per-flow variables (even if ephemeral) and its ability to sustain custom processing at wire-speed, we can for instance implement lightweight measurement of QoS parameters or enforce application-specific congestion control. We have however opted -- in the context of this thesis -- for a focus on another use of the platform: using the ephemeral state to advertise and detect members of distributed applications (e.g. grid computing or peer-to-peer systems) in a purely decentralised way. To evaluate the benefits of this approach, we propose a model of a peer-to-peer community where peers try and join former neighbours, and we show through simulations how efficiency and quality of user experience evolve with the presence of more WASP routers in the network.

Advances in peer-to-peer overlay networks and Semantic Web technology will have a substantial influence on the design and implementation of future digital libraries. However, it remains unclear how best to combine their advantages in constructing digital library systems. This thesis is devoted for investigating, proposing and evaluating possible solutions to advance developments in this field. The main research goal of this work is to combine the strengths of both peer-to-peer overlay networks and Semantic Web for facilitating semantic searches in large-scale distributed digital library systems. The approach has been conducted in a sequential and progressive manner. Firstly, we recognize system infrastructure and metadata heterogeneity as two major challenges in conducting semantic searching across distributed digital libraries. Next, we investigate the strengths and weaknesses of both peer-to-peer and Semantic Web technology and justify that these two fields are complementary and can be combined in conducting semantic searches in a large-scale distributed environment. Thirdly, due to various topologies, functionalities and limitations different peer-to-peer infrastructures may possess, we survey current classical peer-to-peer systems so as to facilitate determinating appropriate infrastructure for specific application scenario. Fourthly, we probe into approaches in generating ontology-enriched metadata records for semantic search purpose. Finally and most importantly, we will propose a semantic search process for interoperation among heterogeneous resources, basing on ontology mapping mechanism. A major contribution expected in our work is, in a broader term, proposing and investigating possible solutions in combining the strengths of both peer-to-peer overlay networks and Semantic Web for facilitating semantic search among highly distributed digital libraries. From a specific perspective, we provide an appropriate benchmark for facilitating decision making in choosing appropriate peer-to-peer networks for digital library construction; especially, we consider in this work no global schema exists and further justify the feasibility and advantages of ontology engineering method in semantic enriched metadata management; to support federated search in such a distributed environment, we also propose an extended super-peer network model, emphasizing in load-balancing and self-organizing capabilities; Based on semantic enriched metadata management, we propose also direct ontology mapping method to enable runtime semantic search process. Evaluation results have illustrated the feasibility and robustness of our approaches. The future direction of this work includes studies on user authentication,efficient ontology parsing and real-life applications.

Numerous control and decision problems in networked systems can be posed as optimization problems. Examples include the framework of network utility maximization for resource allocation in communication networks, multi-agent coordination in robotics, and collaborative estimation in wireless sensor networks (WSNs). In contrast to classical distributed optimization, which focuses on improving computational efficiency and scalability, these new applications require simple mechanisms that can operate under limited communication. In this thesis, we develop several novel mechanisms for distributed optimization under communication constraints, and apply these to several challenging engineering problems. In particular, we devise three tailored optimization algorithms relying only on nearest neighbor, also known as peer-to-peer, communication. Two of the algorithms are designed to minimize a non-smooth convex additive objective function, in which each term corresponds to a node in a network. The first method is an extension of the randomized incremental subgradient method where the update order is given by a random walk on the underlying communication graph, resulting in a randomized peer-to-peer algorithm with guaranteed convergence properties. The second method combines local subgradient iterations with consensus steps to average local update directions. The resulting optimization method can be executed in a peer-to-peer fashion and analyzed using epsilon-subgradient methods. The third algorithm is a center-free algorithm, which solves a non-smooth resource allocation problem with a separable additive convex objective function subject to a constant sum constraint. Then we consider cross-layer optimization of communication networks, and demonstrate how optimization techniques allow us to engineer protocols that mimic the operation of distributed optimization algorithms to obtain an optimal resource allocation. We describe a novel use of decomposition methods for cross-layer optimization, and present a flowchart that can be used to categorize and visualize a large part of the current literature on this topic. In addition, we devise protocols that optimize the resource allocation in frequency-division multiple access (FDMA) networks and spatial reuse time-division multiple access (TDMA) networks, respectively. Next we investigate some variants of the consensus problem for multi-robot coordination, for which it is usually standard to assume that agents should meet at the barycenter of the initial states. We propose a negotiation strategy to find an optimal meeting point in the sense that the agents' trajectories to the meeting point minimize a quadratic cost criterion. Furthermore, we also demonstrate how an augmented state vector can be used to boost the convergence rate of the standard linear distributed averaging iterations, and we present necessary and sufficient convergence conditions for a general version of these iterations. Finally, we devise a generic optimization software component for WSNs. To this end, we implement some of the most promising optimization algorithms developed by ourselves and others in our WSN testbed, and present experimental results, which show that the proposed algorithms work surprisingly well. / QC 20100813

The growth of wireless telecommunications has stipulated the interest for anywhere-anytime computing. The synergy between networking and mobility will engender new collaborative applications with mobile devices on heterogeneous platforms. One such middleware is “SYSTEM ON MOBILE DEVICES”, SYD developed by the Yamacraw Embedded Systems research team. This type of middleware is an opening step towards Peer-to-Peer mobile networks. This project envisioned collaborative applications among mobile devices and PDAs were used as servers. This thesis studies various existing architectures in mobile computing and their scalability issues. We also proposed new scalable flexible thick client proxy system FTCPS, an architecture suitable for mobile Peer-to-Peer networks. Our empirical study showed that FTCPS has low response time compared to other architectures.

Distributed directory services are an evolving paradigm in the distributed computing arena. They are a shift from the centralized directory that causes delay and does not scale well to widespread peer-to-peer networks. With networking becoming more pervasive, there is a need to integrate the heterogeneity of device, data and network with the applications that are built on them. SyD or System on Mobile Devices is a middleware that is being used to implement such a distributed directory service. To provide a persistent global view of data, we serialize and synchronize the distributed directories. The SyD APIs provide a high-level environment to rapidly develop collaborative applications for such networks in a systematic manner. An intervehicle communication application that notifies the driver of a vehicle of the available parking spots in the vicinity, allows us to see the practical working and benefits of the distributed directory paradigm.

No description available.

No description available.

Peer-to-Peer (P2P) computing offers new research challenges in the field of distributed computing. This paradigm can take advantage of a huge number of idle CPU cycles through Internet in order to solve very complex computational problems. All these resources are provided voluntarily by millions of users spread over the world. This means the cost of allocating and maintaining the resources is split and assumed by each owner/peer. For this reason, P2P computing can be seen as a low-cost alternative to expensive super-computers. Obviously, not every kind of parallel application is suitable for a P2P computing environment. Those with high communication requirements between tasks or with high QoS needs should still be performed in a Local Area Networking (LAN) environment. Otherwise, problems with huge computational requirements that can be easily split into millions of independent tasks are suitable for P2P computing, especially as solving these problems with a supercomputer would be extremely expensive. One of the most critical aspects in the design of P2P systems is the development of incentive techniques to enforce cooperation and resource sharing among participants. Incentive policies in P2P distributed computing systems is a new research field that requires specific policies to fight against malicious and selfish behavior by peers. Encouraging peers to collaborate in file-sharing has been widely investigated but, in the P2P computing field, this issue is still at a very early stage of research. Furthermore, the dynamics of peer participation are an inherent property of P2P systems and critical for design and evaluation. This further increases the difficulty of P2P computing. Another critical aspect of P2P computing systems is the development of scheduling techniques to achieve an efficient and scalable management of the computational resources. Unlike file-sharing, based on such immutable resources as files, the mutable ones, such as CPU and Memory are the principal resources involved in P2P computing. Inside the scheduling field, P2P computing can be seen as a particular variant of Grid computing. In a similar way as with the incentive polices, an extensive list of publications can be found that study the scheduling problems for distributed computing, such as Clusters or Grid computing, but few of these focus on P2P computing. For this reason, the scheduling problem in this kind of network is a field that still requires research in depth. In this thesis we propose a Distributed Incentive and Scheduling Integrated Mechanism (DISIM) with a two-level topology and designed to work on largescale distributed computing P2P systems. The low level is formed by associations of peers controlled by super-peers with major responsibilities in managing and gathering information about the state of these groups. Scalability limitations on the first level are avoided by providing the mechanism with an upper level, made up of super-peers interconnected through a logical overlay. Regarding incentives, we propose a mechanism based on credits with a twolevel topology designed to operate on different platforms of shared computing networks. One of the main contributions is a new policy for managing the credits, called Weighted, that increases peer participation significantly. This mechanism reflects P2P user dynamics, penalizes free-riders efficiently and encourages peer participation. Moreover, the use of a popular pricing strategy, called reverse Vickrey Auction, protects the system against malicious peer behavior. Simulation results show that our policy outperforms alternative approaches, maximizing system throughput and limiting free-riding behavior by peers. From the scheduling point of view, the low-level scheduler takes user dynamism into account and is almost optimal since it holds all the status information about the workload and computational power of its constituent peers. Our main contribution at the upper level is to propose three criteria that only use local information for scheduling tasks, providing the overall system with scalability. By setting these criteria, the system can easily, dynamically and rapidly adapt its behavior to very different kinds of parallel jobs in order toachieve an efficient performance. The results obtained proved the efficiency of the overall model and the convergence with the best assignment, achieved with an ideal centralized policy with global information.