"The Web Services Description Language (WSDL) specifies a way to describe the abstract functionalities of a service and concretely how and where to invoke it. The WSDL 2.0 specification does not include semantics in the description of Web services. Therefore, two services can have similar descriptions while meaning totally different things. Resolving this ambiguity in Web services descriptions is an important step toward automating the discovery and composition of Web services, a key productivity enabler in many domains including business application integration.

Semantic Annotations for WSDL and XML Schema (SAWSDL) specification that is being developed by this Working Group defines mechanisms using which semantic annotations can be added to WSDL components. SAWSDL does not specify a language for representing the semantic models, e.g. ontologies. Instead, it provides mechanisms by which concepts from the semantic models that are defined either within or outside the WSDL document can be referenced from within WSDL components as annotations. These semantics when expressed in formal languages can help disambiguate the description of Web services during automatic discovery and composition of the Web services.

Based on member submission WSDL-S, the key design principles for SAWSDL are:

• The specification enables semantic annotations for Web services using and building on the existing extensibility framework of WSDL.
• It is agnostic to semantic representation languages.
• It enables semantic annotations for Web services not only for discovering Web services but also for invoking them."