Research On Adaptive Agent Coordination Framework For Web Services Composition

As the representative of next-generation-Web technology, Web services can solve such problems as the complexity of software interface, difficulties in updating and integrating, etc, which exist in enterprise application environment based on traditional technologies. Moreover, it can build a supply chain for services suppliers and demanders with UDDI protocol. Single Web services just provides limited functionality, it can't provide enough functionalities for practical requirement. In order to solve the integration and collaboration problems of internet applications, it is necessary to compose several Web services together to implement complex business logic functionality. Centric composition engines are widely adopted to enact composite services in many Web service composition research projects. Such a centralized architecture, however, results in problem of scalability, message exchange efficiency, autonomy and adaptation.To deal with the problems discussed above, this paper propose an adaptive Agent coordination framework for service composition, by analyzing some key technologies, discussing some related research projects, and introducing the software Agent technology and combining context-aware with distributed algorithm of flow. The main idea of this framework is: Firstly, to enhance the autonomy and adaptation of service, software Agent represents as Web service. Secondly, the control logic of a composite service and corresponding execution load are distributed into multiple nodes through partitioning the global process model of a composite service into local process models according to the participant services. Lastly, Web service composition system has certain self-adaptive by introducing Agent conversation and context aware. Following efforts are presented in this disssertation:(1) The design of service composition frameworkAbove all, an Agent-based framework for Web services composition is presented in the mass. Its elements as well as the relationship of them are all discussed in detail. Next, agent models of agent-coordination framework are proposed. Lastly, Agent conversation is presented.(2) A service-based decentralized approach for services compositionA directed-graph-based decentralized approach for service composition is proposed. Based on the approach, we set up a decentralized service composition system whose engine is multi-agent system. Simulation results indicate that the performance of service composition system is efficient improved.(3) Self-Adaptation of Service Composition SystemIn order to compose services adaptively, agent coordination framework introduces context aware and agent conversation to realize the adaptability of Web service composition and service access. The self-adaptation can be divided into three groups: self-adaptation of service access, and adaptation of service interaction, self-adaptation of service composition.(4) Web services composition platformThe design and implementation of the services composition framework is presented. This dissertation introduces the process of requirement analysis, general design, detailed design, system design framework, agent model, agent interaction and so on. With an instance, the general design, detailed design, and the execution mechanism which is implemented by a multi-agent system are emphasized.Simulation results indicate that this framework can support highly concurrent requests and large volume of data more effectively than traditional architecture, so it is helpful to improve the scalability of composite services.