Research On Key Techniques Of Web Service Composition For Business Process Integration

With further research and application of Web service, more and more enterprises prefer to package their business as Web services. In the model of business process integration based on Web service, description of abstract business process is separated from its concrete implementation. This feature overcomes the deficiency of traditional workflow technique in business process integration. But the function of single Web service is limited, which cannot fulfill the requirement of process integration at enterprise level. Web service composition can combine multiple simple services together according to business process logic, and therefore it can provide complex and comprehensive business functionality. Moreover, when the business process is changed, automatic and dynamic Web service composition can successfully adapt to the more changeful and dynamic business environment, and new services need not to be rebuilt.Automatic Web service composition relies on the matching of target service description with existing descriptions in the UDDI registry, which will discover the appropriate service. Thus this paper studies automatic Web service composition technology both from behavior description and interface description of Web service. The current standard can only provide syntactic Web service description, and cannot express semantic information. This will decrease the precision of Web service discovery, which cannot guarantee the performance and quality of Web service composition. Therefore we try to upgrade interface matching from syntactic level to semantic level by incorporating semantic into service interface description. Accordingly we have studied semantic Web service composition. Furthermore, in order to overcome the limitations of centralized UDDI registry such as performance bottlenecks and single point failure, we have proposed a kind of distributed Web service catalog system, which supports decentralized Web service publication and discovery. This paper has made research on the following four aspects:(1) Studied Web service composition method based on behavior description. First, analyzed the interaction behavior among activities in business process. Then formalized the inner schema and outer schema of business process based on finite state machine model. In the end, proposed methods for checking existence of composite service, and illustrated the algorithm for computing composite service.(2) Studied Web service composition method based on interface description. First, analyzed the types of Web service composition and message dependency. Then proposed Web service interface matching algorithm with the current standard—WSDL as the Web servicedescription language. In the end, evaluated the matching algorithm by experiments.(3) Studied Web service composition method by extending service interface semantic description. First, extended Service interface semantic description from three levels: message parameter, message and operation, and proposed a lightweight semantic Web service description model. Then proposed service interface semantic matching algorithm from these three levels. In the end, implemented an initial prototype, and illustrated the application of this composition method in business process integration by an example of textile enterprise.(4) Studied distributed Web service publication and discovery technology. First, analyzed the limitations of typical centralized UDDI registry. Then proposed the distributed Web service catalog system utilizing the efficient data location ability of distributed hash table, and discussed the procedure of Web service publication and discovery under this system, as well as the system evolution. In the end, made some improvements for the pure distributed service catalog system, and proposed a kind of hierarchical Web service catalog system according to the hierarchical organization of distributed hash table.