| The development of service-oriented architecture is quickly and the application ofservice-oriented architecture is widely with the rapid development of Internet technology. Webservice which is an important technology of service-oriented architecture has been the populartechnology in the area of distributed computing and electronic commerce for its feature of goodencapsulation, loose coupling, and cross-platform. Recently the Web services in the Internet aremore than before, but a single Web service provides limited functionality, the customers needcomplex service, they want to customize services which meet their requirements. Therefore, wemust compose the existing Web services to meet the customers'demand. How can we composethe services effectively has become a problem in academia and industry.The Web service composition provides the services for customers which satisfies theirrequirements by combining the published services. The nature of the service composition is thereuse of Web services. Currently, the Web service composition methods include servicecomposition based on workflow, service composition based on the formal description, servicecomposition based on artificial intelligence. They are complementary. However, none of theexisting methods considers the issue of service composition reuse. The services are composedfor a demand, when there is another requirement from another customer, we must compose thesame services again. This thesis concerns on the reuse of the composition service and reducingthe complexity of service composition, it has the following results:1,To realize the reuse of composite service, the thesis proposes a component-based servicecomposition method and the complete life cycle of the method. Whether a service is a singleservice or a combined service, we regard it as a component. Service component packaged theinterface, the operations, and the composite logic separately to provide the bases for the use ofservices. This thesis proposes service composite planning language to explain the relationshipbetween services, proposes service component description language to define the component,proposes composite service execution graph to describe the implement structure of compositeservices and to coordinate messages between services when invoking the correspondingservices. Component-based services composition is based on the concept of reuse, extensionfrom component to composite the Web services. This method not only implements the composition but also reuse the composition service to achieve resource sharing. This methodimproves the utilization and efficiency of web component and reduces system overhead.2,To reduce the complexity of service composition, this thesis also proposes a method thatdecomposes a service and extracts the functions which meets with customers' requirements ,and then composes the service though the method based on component. Program slicingtechnique is used in the function extraction for web service. To be able to extract out thefunctions of the service, this thesis proposes the Web service registration based on dependencygraph, the service dependencies between functions is also recorded into the registry whileregistering. |
