Research On Selection Mechanisms For Web Services In Peer-to-Peer Networks

With the development of Internet technologies, Web services has become a burgeoning distributed computing model. With appearance of a great number of Web services, it has become an important subject for the people to quickly find the services desirable to user requirement in the practical application. P2P technology broke the traditional centralized network model. When the idea about P2P and Web services are combined a series of questions which are brought by the centralized Web services discovery can be effectively solved.This dissertation studies the problems of the Web services deployment and selection in P2P networks, and results in the following achievements:(1) A semantic overlay network using the location information of network nodes is presented. A number of the semantic overlay networks are constructed based on P2P networks in accordance with the semantics of Web services. In each semantic overlay network, a group-oriented network system architecture is formed by using the location information of network node. This network structure can reduce the service inquiry cost and management cost, enhance P2P network extendibility.(2) A self-adjusting P2P topology construction protocol based on reciprocity capacity of nodes is presented. This protocol defines reciprocity capacity of a node based on the capacity of providing services and recommending service provider of this node. It makes the nodes which with mutually reciprocity relationship able to fully establish connection. The topological structure using this protocol incents the cooperation between nodes and contains the free-riders and malicious nodes.(3) A P2P Web services search model based on Web services semantics is presented. We get more flexible search function by splitting the Web service semantic search layer and P2P network layer.(4) The service selection problem (meet the requirements of service function and flow behavior) is modeled into multi-attribute decision problem, the decision-making model based on multi-dimensional property of QoS (DQoS) and authorization mode of subjectivity and objectivity combination, provide a basis for selecting high-quality Web Services.(5) The P2P trust model based on groups is developed. In this model, trust relationship is divided into three levels. The node determines the trust value of a specific node by using local trust information and recommendation information (securable within limited time) come from the group which comprises this node, selects Web Service according to trust values of respondents. The trust model make cooperative node in P2P network has a higher successful request rate and node satisfaction value in different malicious node attack mode.