Semantic Web Services
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Semantic Web Services, like conventional web services, are the server end of a client-server system for machine-to-machine interaction via the World Wide Web. Semantic services are a component of the semantic web because they use markup which makes data machine-readable in a detailed and sophisticated way (as compared with human-readable HTML which is usually not easily "understood" by computer programs).
The problem addressed by Semantic Web Services
The mainstream XML standards for interoperation of web services specify only syntactic interoperability, not the semantic meaning of messages. For example, Web Services Description Language (WSDL) can specify the operations available through a web service and the structure of data sent and received but cannot specify semantic meaning of the data or semantic constraints on the data. This requires programmers to reach specific agreements on the interaction of web services and makes automatic web service composition difficult.
Semantic web services are built around universal standards for the interchange of semantic data, which makes it easy for programmers to combine data from different sources and services without losing meaning. Web services can be activated "behind the scenes" when a web browser makes a request to a web server, which then uses various web services to construct a more sophisticated reply than it would have been able to do on its own. Semantic web services can also be used by automatic programs that run without any connection to a web browser.
Choreography vs. orchestration
Choreography is concerned with describing the external visible behavior of services, as a set of message exchanges optionally following a Message Exchange Pattern (MEP), from the functionality consumer point of view.
Orchestration deals with describing how a number of services, two or more, cooperate and communicate with the aim of achieving a common goal.
Semantic Web languages:
- Ontology Inference Layer (OIL)
- DARPA Agent Markup Language (DAML)
- Web Ontology Language (OWL)
- Resource Description Framework (RDF)
- Web Services Modeling Language (WSML)
- Web Services Semantics (WSDL-S)
Semantic Web Service frameworks:
- Ongoing projects funded in the Seventh Framework Programme
- Ongoing and previous projects funded in the Sixth Framework Programme
- Previous projects funded in the Fifth Framework Program
- The ESSI or European Semantic Systems Initiative brings together six European FP6 projects working in the domains of Semantic Web Services and semantically empowered service-oriented architectures.
- QuASAR. Quality Assurance of Semantic Annotations for Services. A project of the school of computer science, University of Manchester.
- SWSI. The Semantic Web Services Initiative is an ad hoc initiative of academic and industrial researchers, many of which are involved in DARPA and research projects funded by the European Community.
- METEOR-S. A project of the LSDIS Lab, University of Georgia and Kno.e.sis Center, Wright State University.
- HALEY. A Web service composition project of the LSDIS Lab, University of Georgia
- 3S@kno.e.sis. Semantics(Services, Science) : The 3S project at the kno.e.sis center, Wright State University, Dayton, OH.
- Belhajjame, K., Embury, S.M., Paton, N.W., Stevens, R. and Goble, A.C., (April 2008). "Automatic Annotations of Semantic Web Services Based on Workflow Definitions". ACM Transactions on the Web 2 (2): 1–34. doi:10.1145/1346337.1346239. http://portal.acm.org/citation.cfm?doid=1346337.1346239.
- Sinuhe Arroyo et al. (2004). Semantic Aspects of Web Services in Practical Handbook of Internet Computing. Chapman Hall and CRC Press. ISBN 1-58488-381-2.
- Cardoso, J., Sheth, Amit (Eds.), (2006). Semantic Web Services, Processes and Applications. Springer. ISBN 0-387-30239-5.
- Zeng, Honglei; T.C. Son (March 2001). "Semantic Web Services" (PDF). Intelligent Systems (IEEE) 16: 46–53. doi:10.1109/5254.920599. http://ieeexplore.ieee.org/iel5/9670/19905/00920599.pdf.
- Kuropka, D.; Tröger, P.; Staab, S.; Weske, M. (Eds.) (2008). Semantic Service Provisioning. Springer. ISBN 3-5407-8616-3. http://www.springer.com/computer/database+management+%26+information+retrieval/book/978-3-540-78616-0. de:Semantic Web Services