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Research On Query Mechanism And Trust Model In Peer-to-Peer Networks

Posted on:2010-01-31Degree:DoctorType:Dissertation
Country:ChinaCandidate:J R WangFull Text:PDF
GTID:1118360302495053Subject:Computer application technology
Abstract/Summary:PDF Full Text Request
Peer-to-Peer Computing (P2P) is the combination of distributed system and computer networks. Rather than the"client/server"mode, nodes in the system connect with each other in a free and equal way. This model of network arrangement breaks up the traditional"client-server"model at network application layer. From the topology view, P2P system can be classified as structured topology and unstructured topology. Structured topology P2P network adopts Distributed Hash Table (DHT) to locate resource. Such network can be easily expanded and the efficiency of querying resource is relative high. But query based on content is not support. Unstructured topology P2P network adopts flooding way to query resource. Such network support complex query and has a simple topology. But efficiency of query is relative low and data may not be located accurately. Besides, good service and reliable resource can not be guaranteed for every node in the system because of the dynamic and anonymity of nodes. With these problems, a deep study of P2P system topology construction, resources query mechanism, as well as nodes trust management is introduced in this article, and has yielded the following results.1.Considering that structured P2P network is lack of content-based query, this paper proposes grouped P2P network based on semantic. This network adopts Vector Space Model (VSM) to summarize the semantic information of shared resource between nodes. Then nodes with similar semantic can be grouped. In each group, unstructured network is adopted. At the same time in a group nodes with greater ability are selected as super nodes and super nodes formed structured network. The simulation shows that such structure of network reduces the cost of resource query, and provides effective support for content-based query.2.Combining with the flooding search mechanism of unstructured P2P network, this paper introduces a novel unstructured P2P network based on Small-world theory. This unstructured P2P system is designed in accordance with the principle "Birds of a feather flock together" in Social Networks, such unstructured P2P system makes nodes with similar semantic clustered, so that the network has a high clustering coefficient and smaller average path length, significantly improving the efficiency of the network query.3.In P2P network system, as nodes are dynamic and anonymous, the system lacks effective supervising and managing to nodes'behavior. Establishing trust model in the system is a feasible solution. In view of the semantic grouped P2P network, this paper proposes group based trust model. In grouped P2P network, super nodes have more online time and powerful computing ability, so global trust model is used in the structured layer, and local trust model is used inside groups. Experiments show that this trust model can resist attacks from malicious nodes and has good effectiveness and robustness.
Keywords/Search Tags:Peer-to-Peer Computing, Information Retrieval, Clustering, Small World, Trust Model
PDF Full Text Request
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