Finding information in a peer-to-peer system currently requires either a costly and vulnerable central index, or ooding the network with queries. In this paper we introduce the concept of Routing Indices (RIs), which allow nodes to forward queries to neighbors that are more likely to have answers. If a node cannot answer a query, it forwards the query to a subset of its neighbors, based on its local RI, rather than by selecting neighbors at random or by ooding the network by forwarding the query to all neighbors. We present three RI schemes: the compound, the hop-count, and the exponential routing indices. We evaluate their performance via simulations, and nd that RIs can improve performance by one or two orders of magnitude vs. a ooding-based system, and by up to 100 % vs. a random forwarding system. We also discuss the tradeo s between the di erent RIschemes and highlight the e ects of key design variables on system performance.

Despite their growing popularity, the behavior of super-peernetworks is not well understood. For example, what are the potential drawbacks of super-peer networks? How can super-peers be made more reliable? How many clients should a superpeer take on to maximize efficiency? In this paper we examinesuper-peer networks in detail, gaining an understanding of their fundamental characteristics and performance tradeoffs. We alsopresent practical guidelines and a general procedure for the design of an efficient super-peer network.

Distributed computer architectures labeled “peer-to-peer ” are designed for the sharing of computer resources (content, storage, CPU cycles) by direct exchange, rather than requiring the intermediation or support of a centralized server or authority. Peer-to-peer architectures are characterized by their ability to adapt to failures and

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In a peer-to-peer (P2P) system, nodes typically connect to a small set of random nodes (their neighbors), and queries are propagated along these connections. Such query flooding tends to be very expensive. We propose that node connections be influenced by content, so that for example, nodes having many "Jazz" files will connect to other similar nodes. Thus, semantically related nodes form a Semantic Overlay Network (SON). Queries are routed to the appropriate SONs, increasing the chances that matching files will be found quickly, and reducing the search load on nodes that have unrelated content. We have evaluated SONs by using an actual snapshot of music-sharing clients. Our results show that SONs can significantly improve query performance while at the same time allowing users to decide what content to put in their computers and to whom to connect.

Peer-to-peer systems have emerged as a popular way to share huge volumes of data. The usability of these systems depends on effective techniques to find and retrieve data; however, current techniques used in existing P2P systems are often very inefficient. In this paper, we present three techniques for efficient search in P2P systems. We present the design of these techniques, and then evaluate them using a combination of experiments over Gnutella, the largest open P2P system in operation, and analysis. We show that while our techniques maintain the same quality of results as currently used techniques, our techniques use up to 5 times fewer resources. In addition, we designed our techniques to be simple in design and implementation, so that they can be easily incorporated into existing systems for immediate impact. Keywords: Peer-to-peer, distributed data, search, performance modeling, evaluation Technical Area(s): Databases, performance modeling and evaluation 1

In this paper, we present the design and evaluation of PeerDB, a peer-to-peer (P2P) distributed data sharing system. PeerDB distinguishes itself from existing P2P systems in several ways. First, it is a full-fledge data management system that supports fine-grain content-based searching. Second, it facilitates sharing of data without shared schema. Third, it combines the power of mobile agents into P2P systems to perform operations at peers' sites. Fourth, PeerDB network is self-configurable, i.e., a node can dynamically optimize the set of peers that it can communicate directly with based on some optimization criterion. By keeping peers that provide most information or services in close proximity (i.e, direct communication), the network bandwidth can be better utilized and system performance can be optimized. We implemented and evaluated PeerDB on a cluster of 32 Pentium II PCs. Our experimental results show that PeerDB can effectively exploit P2P technologies for distributed data sharing.

One important problem in peer-to-peer (P2P) networks is searching and retrieving the correct information. However, existing searching mechanisms in pure peer-to-peer networks are inefficient due to the decentralized nature of such networks. We propose two mechanisms for information retrieval in pure peer-to-peer networks. The first, the modified Breadth-First-Search (BFS) mechanism, is an extension of the current Gnuttela protocol, allows searching with keywords, and is designed to minimize the number of messages that are needed to search the network. The second, the Intelligent Search mechanism, uses the past behavior of the P2P network to further improve the scalability of the search procedure. In this algorithm, each peer autonomously decides which of its peers are most likely to answer a given query. The algorithm is entirely distributed, and therefore scales well with the size of the network. We implemented our mechanisms as middleware platforms. To show the advantages of our mechanisms we present experimental results using the middleware implementation.

The development of new services through the integration of existing ones has gained a considerable momentum as a means to create and streamline business-to-business collaborations. Unfortunately, as Web services are often autonomous and heterogeneous entities, connecting and coordinating them in order to bu ild integrated services is a delicate and time-consu ing task. In this paper, we describe the design and implementation of a system throuk which existing Web services can be declaratively composed, and the resu lting composite services can be execu ted following a peer-to-peer paradigm, within a dynamic environment. This system provides tools for specifying composite services throu. statecharts, data conversion ru les, and provider selection policies. These specifications are then translated into XMLdocu ents that can be interpreted by peer-to-peer inter-connected software components, in order to provision the composite service without requiring a central authority.

In this paper, we study a peer-to-peer media streaming system with the following characteristics: (1) its streaming capacity grows dynamically; (2) peers do not exhibit serverlike behavior; (3) peers are heterogeneous in their bandwidth contribution; and (4) each streaming session may involve multiple supplying peers. Based on these characteristics, we investigate two problems: (1) how to assign media data to multiple supplying peers in one streaming session and (2) how to fast amplify the system’s total streaming capacity. Our solution to the first problem is an optimal media data assignment algorithm ÇÌËÔ Ô, which results in minimum buffering delay in the consequent streaming session. Our solution to the second problem is a distributed differentiated admission control protocol ���Ô Ô. By differentiating between requesting peers with different outbound bandwidth, ���Ô Ô achieves fast system capacity amplification; benefits all requesting peers in admission rate, waiting time, and buffering delay; and creates an incentive for peers to offer their truly available out-bound bandwidth.