Specifying and Composing Web Services with an Environment Ontology-Based Approach

Precise capability specification is the key for identifying and composing the right Web services. This paper specifies service capabilities in terms of the environment entities from the application domain and the effects imposed by the Web service on these entities. An environment ontology for Web services is adopted to provide formal sharable representations of the domain-specific environment entities. A hierarchical state machine is constructed for each environment entity to describe its behaviors, and the effects imposed by a Web service are described as the state transitions traces of environment entities, which define the capability of the Web service. Web service composition that satisfies a set of requested effects is then conducted by reasoning on the effects of services. The proposed approach emphasizes the external manifestation of Web services and service composition based on the effect reasoning. An example of online travel service illustrates the proposed approach.