Automatic Semantic Web Services Composition

Web service is a self-contained, self-described, modular applications that can adopt open standards to provide services to users, to support specific business functions. With the development of Internet technology, more and more information is provided to users in the form of Web services. But a single Web service features simple, and often is insufficient to meet the needs of users. So we need to compose a number of existing services to create a larger size and more powerful Web services in order to achieve business objectives. Due to the lack of information of semantic description, the function of web services can’t be described accurately. So the semantic information is introduced into the Web services composition technology.This study propose a semantic Web services automatic composition method based on user request input closure and backward tree. Some related theories and technology used in the semantic Web services and ontology have been studied and discussed. Firstly, the method uses the concept of ontology to annotate Web services and user requests and then transforms the semantic Web service repository to semantic Web service rule repository after expressed formally. Secondly, the method build a user request input closure according to the given user request. In dealing with user requests, it judges whether user requests can be met in the given semantic Web service rule repository according to user request input closure to limited the search space in the user request input closure. When user request is not satisfied, it illustrates the request has no solutions,the algorithm ends with reducing the overhead of request processing; Otherwise, it constructs backward tree for each output object in user request,and prunes the process of constructing backward tree by user request input closure and setting object set of new node. Then it judges whether the new node is optimal valid generation source. Finally, we elaborate the semantic Web services automatic composition method is feasible and effective by simulation example in detail.