Research On OWL-S-based Annotation Techniques For Web Services

Traditional Web Services technology (SOAP, WSDL, UDDI and so on) lacks machine-understandable semantics, which has limited the automation of Web Services. It is the central issue of the next generation of Web Services—Semantic Web Services that how to express information about Web Services (its usage, functionality and access) in a machine-processable way, i.e., being attached with formal semantics.On the basis of the existing research results, this paper puts forward an OWL-S (the Semantic markup language for Web Services) based framework named WSAnnotator for the annotation of Web Services. This framework can annotate atomic services and simple composite services composed of atomic services in a sequential execution mode. The annotation process of an atomic services starts from the WSDL document of the services. The XML terms in the WSDL document are semantically marked up with the vocabulary of the OWL domain ontologies. After adding some necessary services description information, the OWL-S description of the services (i.e., the instance of the Services Ontology and its subontologies Profile, Process and Grounding) is then automatically generated from the WSDL document by following a set of predefined mapping rules from WSDL to OWL-S. The annotation of a simple composite service based on the annotated atomic services. The OWL-S description of the composite service is automatically generated by following certain rules and algorithmic steps, utilizing OWL-S "Sequence" constructor, and combining the OWL-S descriptions of the atomic services. WSAnnotator has been implemented as a prototype system. Case study shows that the proposed approach is feasible.Compared with the other approches/tools, WSAnnotator has the following characteristics: (1) it can annotate not only atomic Web Services but composite services composed of atomic services in a sequential execution mode, (2) the annotation output is the normative OWL-S description of Web Services, and (3) the semantic description of Web Services is more complete. In conclusion, the research result is of certain practical significance to the promotion of the automation of Web Services.