The Web Service Modeling Ontology

In the previous chapter we have identified several aspects of services that need to be described in order to effectively find and use these services. This includes the functional and nonfunctional description of the service, as well as a description of the behavior and the interface. We have also identified the need for common terminologies and suggested the use of ontologies for their description; using a common vocabulary across descriptions is a prerequisite to be able to match descriptions of Web services and user requirements.

The Web Service Modeling Ontology WSMO [57, 121] provides a conceptual model for the description of Web services. WSMO distinguishes between user goals, which are descriptions of the desires of the requester, and Web servicedescriptions, which are descriptions of the functionality and interface of the service offered by the provider. Thereby, WSMO acknowledges the separation between the requester and provider roles.

Another important principle ofWSMO is the loose coupling of the descriptions of goals and Web services, allowing them to be described independently. Mediators(first identified in [138]) are used for overcoming possible discrepancies in the terminology and styles employed in the descriptions.