Towards a Unified Model for Web Services Composition

The web services paradigm, which finds roots in Service-Oriented Computing [ACKM04,PG03], promises to enable rich, flexible, and dynamic interoperation of highly distributed and heterogeneous web-hosted services. Substantial progress has already been made towards this goal (e.g. emerging standards such as SOAP, WSDL, BPEL) and industrial technology (e.g., IBM's WebSphere Toolkit, Sun's Open Net Environment and JiniTM Network technology, Microsoft's .Net and Novell's One Net initiatives, HP's e-speak). Several research efforts are already underway that build on or take advantage of the paradigm, including the DAML-S/OWL-S program [OWL-S,MSZ01,Gru03, SPAS03], the Semantic Web Services Initiative (SWSI) [SWSI] and Web Service Modeling Ontology (WSMO) [WSMO] groups, and automata-based and other models for web services [[BFHS03,HBCS03,BCG+03,BCH05]. A key research challenge in web services concerns (semi-)automatic discovery and composition of web services, in order to construct new web services with desired properties or capabilities. This extended abstract provides a short review of selected works in this young and ambitious area. A more comprehensive overview of this area may be found in [HS05]. However, the reader is urged to consult the primary sources for a much more complete discussion of both the results obtained so far, and the questions that are motivating further investigation.