Research And Application Of Goal-based Narrowing Approach For Semantic Web Service Composition

Web service is a kind of distributed computing model, which develops very prosperously recently; it can operate seamlessly between applications or application components designed by different programming language in different platforms. With the development of web service platform and the increasing number of available web services on the Internet, in order to enhance the reuse and accuracy of Web Service and reduce the development cost, it is necessary to discover, compose and execute Web Service effectively. However, the current WSDL lacks semantic information of service description and the discovery of UDDI is keyword-based, obviously they don't meet the requirements for the discovery and composition of Web Services. On the other hand, the research of Semantic Web has greatly developed. Introducing semantic web technology into web service domain gives birth to a new technology——Semantic Web Service. The semantic Web markup language can be used to describe the semantics of Web Services and make them computer-interpretable entities, which makes the dynamic discovery, composition and execution of Web Services possible.This thesis is focus on the dynamic discovery and composition of web service on the semantic web, the aim is to compose the various Web services automatically in accordance with the demands of customers, and to complete the task corporately, by which we can make the services meet the requirements of customers according to their specific demands. Taking the tourism information system as application background, the main contents of this paper can be summarized as follows:①This thesis introduces firstly the concepts, the architecture and related technologies of web services and then the current research situation of web services composition.②According to the existing standards, this paper classifies and compares the current discovery and composition methods. Compares typical methods based on the standards proposed in exsiting literatures.③This paper analyzes the shortage of these methods based on solving real-time tasks----large sums of semantic services matching algorithm only use input and output parameters to describe the functions of web services, which is insufficient to discover and composite related services. This paper proposes a modeling method to describe the pre/post conditions of web services, describes the web services not only by the inputs and outputs but also by the pre/post conditons of web services, and then gives the formal definition of web services discovery and composition.④This thesis introduces a goal-based narrowing method to discover and composite web services by establishing a forward chain, and describes the framework to implement this method. The experiment results show that this model can correctly discover and composite the required services in a short time according to the inputs/outputs and the pre/post conditions, which reflects the advantages in both performance and processing. Finally, this paper gives a summary of our work and discusses the next step of this work.