Research On Semantic Web Service Composition Based On Multi-agent Task Decomposition And QoS

Web service and Semantic Web are the two important trends which are emerging in the World Wide Web (WWW). These two researches have complement each other very well. The confluence of Web services and the Semantic Web gives birth to another new technology----Semantic Web Services. The Semantic Web markup language can be used to describe the semantics of Web services and make them computer-interpretable entities, so as to enable programs or agents to find, invoke and compose Web services automatical and so on.At present composing the existing Web services according to corresponding semantic and logic to get value-added services is the hot issues of Web service research domain. Under the circumstances, this dissertation discusses several key issues in Semantic Web services composition automation, including Semantic Web markup language, Semantic Web services description model and Web services composition method. The main points of the dissertation are described as follows:Firstly, the dissertation introduces the knowledge about semantic web, Web service, Ontology and its description language, Ontology modeling and Agent technology, including their latest research progress.Secondly, by describing, comparing, and analyzing the traditional Web Service combination technique, the disadvantage of traditional methods is indicated. The idea of the dissertation puts forward is a semantic Web service composition system can be considered as a multi-agent system(MAS). In the MAS, detailed analysis of all Agent function are given, and a Web services selection method and its mathematical computing model based on Task Decomposition and Quality of Service(QoS) constraint are proposed.Thirdly, in MAS, a new semantic web service composition model based on task decomposition and QoS constraint is proposed. In this model, requires of clients are decomposed to many subtasks which can carry out separately, the service of every subtask is matched by their semantic, and choice of services are obtained by computing the service quantity indexes of each subtask, so a combination of service sequence meet users is brought. Simulation experiments based on manual Ontology database are given to prove that this model is effective and useful. In all, the dissertation puts forward to apply Agent technology and Semantic Web to Web Service composition, correlative Web services are selected by task decomposition and QoS constraint. Then semantic web service composition model is proposed for these. The model to some extent achieves intelligentize and semantization of Web Service Composition.