Abstract. Current research in peer to peer systems is lacking appropriate environments for simulation and experimentation of large scale overlay services. This has led to a plethora of custom made simulators that waste development resources and hinder fair comparisons between different approaches. In this paper we present a new simulation / experimentation framework for large scale overlay services with three main contributions: i) provide a unifying approach to simulation/ experimentation that eases the transition from simulation to network testbeds, ii) it clearly distinguish between the design of overlay algorithms (key based routing), and the applications and services built on top of them, iii) offer a layered and modular architecture with clear hotspots, and pervasive use of design patterns. We have used PlanetSim to implement and evaluate overlay networks such as Chord and Symphony, and overlay services such as Scribe application level multicast, and keyword query systems over distributed hash tables.
Abstract.As Structured Peer-to-Peer (P2P) Networks become popular, there is an emerging need to monitor continuously the huge number of participants in a robust and scalable manner. To this end, aggregation has emerged as a basis for the self-management of these networks. However, the structured P2P networks lack today of efficient mechanisms for the decentralized computation of these aggregates. In this paper, we propose a hierarchical theoretic model based on Cayley Graphs, which overcomes the requisite to accommodate growth without impacting the efficiency of distributed applications. Also, the paper presents an aggregation protocol that fuses the fault-resilience of gossip algorithms with the scalability of trees. In particular, simulation results show that this algorithm is capable to cope with the distributed and unreliable nature of P2P networks.
International audienceIn this paper we present Damon, a new distributed aspect-oriented composition model. Our model mimics the CCM and is based on computational reflection, component-based design, and separation of concerns. Moreover, we benefit from the peer-to-peer substrate to implement these services in a decentralized and efficient way. Damon aims to provide new distributed concerns (i.e. replication) to existent or new applications transparently. It reduces the complexity of application development and allows runtime reconfiguring. The innovative contributions of our approach are composition capabilities in design, load-time and runtime phases, including the definition of distributed aspects and meta-aspects
Many computer vision techniques need the detection of edges in the image as a first step of an image understanding process. In some cases, a grey-level edge detector is not rich enough to describe changes that are present in the image and the use of colour information and colour edges is a valuable tool for some problems. In this paper, we propose a distance function in the colour space to measure the perceived difference between two colour vectors. This function is further used combined with some concepts of the Canny edge detector to define a novel approach to colour edge detection. The experiments carried out show that the proposed method for colour edge detection provides satisfactory results both in synthetic and real colour images.
In this paper we present the p2pWeb service oriented architecture (SOA). The p2pWeb model offers decentralized solutions for service description, publication, discovery and availability, following the web services standards. The three innovative contributions in p2pWeb SOA are: easy integration of web services into a p2pWeb network, secure and decentralized web services deployment, and transparent location, load balancing and faulttolerance peer-to-peer mechanisms. We believe that all the features our p2pWeb model offers can be of special interest for the creation of communities, and for the development of future collaborative decentralized applications.
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