Research On A New Two-layered P2P Architecture Model

Peer-to-Peer computing(P2P)is a new network model that has been sweeping through the computing industry over the past year or so. Being supported by distributed computing technology, P2P has several special features. In a P2P-based system, each peer has equal functionalities and responsibilities: each peer can act both as server to supply resource, and as client to utilize resource provided by other peers. Furthermore, the interaction among peers can be direct and symmetric without relying on the centralized server. In addition, peers can join in or leave from the system at any time to form dynamic network environment. Compared with the traditional Client/Server model, P2P has many advantages, such as scalability, self-organization, anonymity, dynamicity, robust, the elimination of bottleneck caused by centralized servers and the higher utilization of network resources. For these reasons, there is great potential to apply P2P technology.A fundamental problem that confronts peer-to-peer (P2P) applications is to construct an efficient system which can support semantic search. This paper presents CTL-P2P, a cluster-based two-layered P2P architecture model that addresses this problem. CTL-P2P is a combination of structured topology and unstructured topology. It utilizes interest and behavioural peer clustering to form clusters. Each cluster is an unstructured topology, use heterogeneity to select super-peers as local servers of clusters. Super peers constitute the high-level structured topology. Results from theoretical analysis and simulations show that CTL-P2P is scalable, with low maintenance cost, high search efficiency and stable network traffic. The main contributions are as follows:(1)To the best of our knowledge, our research is the first attempt to take into consideration of heterogeneity and clustering to construct a two layer P2P network which is composed of structured layer and unstructured layer. It combines the benefits of each aspect.(2)Focus on the node clustering problem, this paper presents a new theory based on Latent Semantic Index in P2P network node fuzzy clustering. It utilizes TF-IDF weighting technology to describe the resources of nodes and then return eigenvectors. After that, combine of the semantic-oriented interests and user behavior for calculating the similar degree between nodes, this method constructs fuzzy similar matrix, find the cut-off matrix to complete the node clustering.(3) Based on the two-layered P2P network, this paper has done some research work on the cluster location algorithm,node joining algorithm, cluster dynamic updating algorithm, cluster splitting method and query forwarding algorithm.(4) Based on the key techniques described above, we have implemented CTL-P2P: a prototype of cluster-based two-layered P2P system. Results from simulations and theoretical analysis show that CTL-P2P is scalable, with low load of bandwidth, high search efficiency and stable network traffic.In a word, this thesis has detailed the design, key techniques and experimental results of a cluster-based two-layered P2P network, which have been realized in CTL-P2P. All these contributions are achieved through a comprehensive study on the related theories, existing technologies and experimental results. Moreover, the experimental results have verified such a P2P-based information retrieval system can realize fully semantic information retrieval and sharing of fine granularity, and efficiently utilize the system's resource as well.