Creating Bioinformatics Semantic Web Services from Existing Web Services: A Real-World Application of SAWSDL

Semantic annotations for WSDL (SAWSDL) is a recently adopted W3C recommendation that provides a mechanism by which WSDL documents can reference external, domain-specific semantic models in order to provide concept-level interoperability of Web Services. Moby is an established protocol for providing semantic Web Services developed by the bioinformatics community: we use Moby to provide a grounding for a SAWSDL implementation in bioinformatics. Our software (Daggoo) allows users to create Moby-compliant semantic Web Services by simply adding SAWSDL markup to existing WSDL files. These new services are compatible with existing Moby services and client software. The Java software we present consists of a proxy servlet, a URI-resolution mechanism, and rule systems for converting back and forth between Moby and XML Schema data formats. As an early implementation of SAWSDL, Daggoo reveals shortcomings in the notation, and several additional technologies needed to achieve real-world semantic interoperability of WSDL-based services. Based on our experience, we suggest how to improve the semantic annotation mechanism, and how to reduce the programming burden for individual service providers. Furthermore, we demonstrate the importance of a semantically-enabled registry for services and data types in facilitating scientist-driven, rather than programmer-driven, Web service choreography.