The Solution To Some Crucial Problems Of Web Service Composition

This project is supported by National Natural Science Foundation of China, No.90204010 (from 2003.1 to 2005.12).As web services become more and more prevalent, tools that can help users find, filter and integrate these services are badly needed. Composing existing services to obtain new functionality is important for various areas such as business-to-business, business-to-consumer applications and enterprise application integration. Firstly, all kinds of existing techniques for service composition are studied. And a general framework for web service composition is proposed to show the components of a service composition system and the process of the service composition. Exact service composition relies on the semantic web technique. The first step is to add semantics to the web service descriptions. One approach is to semantically annotate the existed web services based on the shared ontology. And the other is to model and descript web services by the means of semantic web technique. The dynamic composition of services requires the location of services based on their capabilities to find those services that can be matched together to create a new service. So semantic matching of web service capabilities is needed. The paper defines matching degree to show how much a service matches a required service and provides the method to compute it. And then a simple algorithm for semantic location of services is provided. At last, service composition algorithms are studied. An interface-matching algorithm is proposed, but it has lots of short points and is not practical. Semi-automatic service composition is more practical. So a prototype for semi-automatic composition, which guides a user in the dynamic composition of web services, is developed and relevant algorithms are proposed. Based on the prototype and the algorithms, a service composition system is implemented and tested.