Research On Key Technologies Of Service Recomposition Of Service-Oriented Architecture

Web service is at the core of SOA (Service Oriented Architecture). In order to enhance the usability and dependability of web service, it is a key problem to perform efficient recomposition on web service. Web service recomposition covers wide range of aspects. Among all aspects, description and matching of web service, modeling of workflow based on web service, service composition and recomposition of web service on SOA are the focuses of research. To study on these aspects has very important theoratic meanings and pratical values.On the basis of analyzing the deficiencies of current methods, a description method combining XML and UML is proposed. XML is used to fully describe web service. UML is used to arrange description information and gives users direct, layered and emphases prone view of the whole description. On the basis of resolving service description problem, from the point of human recognition, a matching method is discussed. In order to achieve balance between matching efficiency and cost, UML is used to perform cursory matching, and XML is used for comprehensive matching. The basis of the web service recomposition is then laid out.On the basis of analyzing the common workflow modeling methods and the current modeling method based on Petri net, characteristics of workflow based on web service are discussed, and new workflow modeling method based on multi-agent and time extended is proposed. In this solution, life cycle idea is imported to manage web service under open internet circumstance, and the idea is combined with Agent technology to expand workflow. Agent is modeled from static description, dynamic description and communication protocol aspects, and cube framework is used to separate administrative data and description data between providers and users. A good platform for web recomposition is built on this basis.Aiming at the advantages and deficiencies of these methods, on the basis of analyzing the characteristics of natural evolution, modifications are made on the Genetic Algorithm. A BMGA (Balanced Multi-objective Genetic Algorithm) is proposed. The definition, implementation steps and convergence testimony are given. BMGA can be executed either on a standalone Agent or on several Agents at the same time; and Agent can adopt BMGA or other algorithm under the condition of satisfying the static, dynamic and communication protocol.Aiming at enhancing the dependability, a kind of LCSN (Layered Creditable Service Network) is proposed. Static structure of LCSN includes Plate Ring and LCSN tree. Different layer of LCSN tree represents different abstract level conception, and all services in a Plate Ring or node containing web services information have some similarity. Using LCSN, find substitute service when a service is broken down can be achieved and reduce the labor finding an appropriate service in the sea of services. Combining with BMGA, LCSN can provide a better swatch space, and then can make BMGA get satisfactory solutions faster and better.A web application system is used to depict the implementation of SOA system.Through the research on web service recomposition technologies, some fruits that have theoretic values and application values are achieved, and lay theretic and method foundations for the further application systems.