Combining RDF and OWL with SOAP for Semantic Web Services

This paper has two contributions: (1) we attempt to propose that a combination of RDF and OWL with SOAP is useful for building semantic Web services (SWS); (2) we show how to combine them technically. A SOAP Envelope comprises Header (control data) and Body (transaction data). They are defined in XML schema syntactically not semantically, resulting in inflexibility for Web services invocation. RDF and OWL introduce ontology-based semantics into SOAP. We provide four-level SWS: three-level combinations plus a base level for easy comparison. SWS at Level 0 (Internal Translation) can process multiple data formats by internally translating one format in SOAP into others. SWS at Level 1 (Simple Reference) use pointing a link with an OWL individual in SOAP and allow service receiver(s) to decide whether or not to process it. They are useful for such business use cases as product/service introduction and promotion. SWS at Level 2 (Direct Embedment) embed an OWL individual in SOAP Envelope and define the types of messages in WSDL by using OWL classes instead of XML Schema. They are useful to add semantics gradually into current Web service infrastructure. SWS at Level 3 (Semantic SOAP) relax nearly all constraints in WSDL to receive/send, understand, and process semantic SOAP, encoded in a general ontology. They are useful for casual integration and for agents that have never met before.