Research On Automated Semantic Web Service Composition And Verification

The emergence of Service-Oriented Architecture (SOA) and Service-Oriented Computing (SOC) provides a flexible solution for building distributed applications and integration of enterprise information systems. Because of the limitation of the function of a single Web service, how to combine multiple Web services together to complete a complex task has become the key concern of industry and academia. At the same time, by combining the technologies of Web service and Semantic Web, a variety of semantic Web service frameworks are proposed, which can be used to enable the automated Web services discovery, composition, verification and implementation.Under the support of the national 863 project "solution-oriented service architecture and supporting environment", we study in-depth the key approaches for Semantic Web service composition, including Web service discovery, Web service composition and Web service process verification. The main contributions of this paper are listed as follows:1) We studied the relationship between Web services and improved the concept of service networks. In combination with the technologies related to semantic Web services, and from the perspective of service functions, we presented the concepts of abstract service and concrete service. Beside this, we analyzed and defined diferent potential relationships respectively in four different levels of granularity including the parameter, operation, concrete service and abstract service levels. And finally, we gave the conceptual framework and system architecture of the service network.2) We studied the problem of the composition of information providing Web services, and proposed a GraphPlan based heuristic algorithm for service composition. Based on the characteristics of the information providing Web services, the algorithm divided the service composition process into two phrases including service planning graph creation and solution searching, and can determine the satisfiability of the problem of service composition in polynomial time. In the course of the construction of the service planning graph, we took full account of relationship information in the service network, and the algorithm of the solution searching was designed to utilize a novel heuristic selection strategy.3) We studied the problem of the hybrid service composition which included both information providing services and world state changing services, and proposed a service composition system based on the abstract template. This system is only concerned with the abstract services in the service network, and given a user's functional requirement, it can complete the construction of an abstract service composition process throuth reusing the past experiences of solving the old similar requirements or by the template preprocessing and heuristic template adaptation. Experimental results showed that in the same external environment, our system can achieve the service composition task in a relatively short time with the increasing of the number of services, and have a better flexibility.4) We studied the problem of the verification of the semantic Web service processes, and proposed an consistence verification approach based on Petri nets models. This approach can find the potential logical inconsistence of the semantic Web service process before the deployment of it, thus enhancing the robust of the process and the users'satisfaction. And through a practical case, we proved the correctness and effectiveness of this approach.