Using assumptions in service composition context

Service composition aims to provide the efficient and accurate model of a service, based on which the global service oriented architecture (SOA) can be realized, allowing the value-added services to be generated on the fly. Because of distributed responsibilities, ownership, and control, often, it is not feasible to acquire all information needed for the service composition, thus there might be no guarantee that the service execution has an anticipated effect. In this paper, we are going to extend current Semantic Web Service Description by introducing the concept of Service Assumption which allows reasoning with incomplete information. Furthermore, together with the proposed service assumption, a sequence of rules is developed to describe all permitted behaviors in service composition context

Semantic Service Description Framework for Efficient Service Discovery and Composition

Web services have been widely adopted as a new distributed system technology by industries in the areas of, enterprise application integration, business process management, and virtual organisation. However, lack of semantics in current Web services standards has been a major barrier in the further improvement of service discovery and composition. For the last decade, Semantic Web Services have become an important research topic to enrich the semantics of Web services. The key objective of Semantic Web Services is to achieve automatic/semi-automatic Web service discovery, invocation, and composition. There are several existing semantic Web service description frameworks, such as, OWL-S, WSDL-S, and WSMF. However, existing frameworks have several issues, such as insufficient service usage context information, precisely specified requirements needed to locate services, lacking information about inter-service relationships, and insufficient/incomplete information handling, make the process of service discovery and composition not as efficient as it should be. To address these problems, a context-based semantic service description framework is proposed in this thesis. This framework focuses on not only capabilities of Web services, but also the usage context information of Web services, which we consider as an important factor in efficient service discovery and composition. Based on this framework, an enhanced service discovery mechanism is proposed. It gives service users more flexibility to search for services in more natural ways rather than only by technical specifications of required services. The service discovery mechanism also demonstrates how the features provided by the framework can facilitate the service discovery and composition processes. Together with the framework, a transformation method is provided to transform exiting service descriptions into the new framework based descriptions. The framework is evaluated through a scenario based analysis in comparison with OWL-S and a prototype based performance evaluation in terms of query response time, the precision and recall ratio, and system scalability

Using assumptions in service composition context

Service composition aims to provide an efficient and accurate model of a service, based on which the global service oriented architecture (SOA) can be realized, allowing value added services to be generated on the fly. Unlike a traditional software module, which runs within a predictable domain, Web Services are autonomous software agents running in a heterogeneous execution environment. Because of distributed responsibilities, ownership and control, it is often not feasible to acquire all information needed for the service composition. These characteristics of autonomy and heterogeneity are fundamental to service oriented computing but make it inherently difficult to avoid service conflicts. To reason about and adapt to a changing environment, in this work, we will extend current OWL-S by introducing the concept of service assumptions which allow reasoning with incomplete information. Furthermore, together with the proposed service assumptions, a sequence of rule conditions are proposed to describe all permitted behaviors in service composition context