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Semantics of Web Services

Semantics of Web Services. Asuman Dogac Middle East Technical University Software R &D Center Ankara, T ü rkiye. Why do we need Web Service Semantics?. In order to exploit services in their full potential their properties must be defined: The methods of charging and payment

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Semantics of Web Services

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  1. Semantics of Web Services Asuman Dogac Middle East Technical University Software R&D Center Ankara, Türkiye Grenoble Ecole de Management MEDFORIST Workshop

  2. Why do we need Web Service Semantics? • In order to exploit services in their full potential their properties must be defined: • The methods of charging and payment • The channels by which the service is requested and provided • Constraints on temporal and spatial aspects • Availability • Service quality • Security, trust and rights attached to a service Grenoble Ecole de Management MEDFORIST Workshop

  3. Why do we need Web Service Semantics? • To be able to describe service properties • and later search for services according to their properties • This search needs to be done in a machine processable and interoperable manner • This in turn is possible only by describing the semantics of Web services through ontology languages Grenoble Ecole de Management MEDFORIST Workshop

  4. WSDL does not describe Web service semantics Semantic description of the properties of a service in DAML-S Web Service Description defines uses Service Consumer Web Service Grenoble Ecole de Management MEDFORIST Workshop

  5. Taxonomies are not enough to define service semantics:An Example Taxonomy: UNSPSC 43.00.00.00.00 Communications and Computer Equipment and Peripherals and Components and Supplies 43.16.17.00.00 Business Transaction and Personal Business Software 43.16.17.02.00 Tax Preparation Software Grenoble Ecole de Management MEDFORIST Workshop

  6. An Example Ontology for Travel Domain TravelService Transportation Service Accommodation Service Entertainment Service AirTransportation ReserveAFlight BuyATicket Grenoble Ecole de Management MEDFORIST Workshop

  7. ReserveAFlight originatingFrom destinationTo paymentMethod Properties of ReserveAFlight Generic Service How to relate MyService to a generic service class? MyService Grenoble Ecole de Management MEDFORIST Workshop

  8. Ontology Languages • Resource Description Framework • DAML+OIL by • DARPA and • On-To-Knowledge project (European Commission, IST-1999-10132) • Extends RDF with more sophisticated class and property definitions • OWL (Web Ontology Language) by W3C • Based on DAML+OIL • DAML-S by DAML Services Coalition Grenoble Ecole de Management MEDFORIST Workshop

  9. Ontology Languages • Have formal specification and thus can be queried • Provide the means to define sophisticated class properties Grenoble Ecole de Management MEDFORIST Workshop

  10. Resource ServiceProfile presents: What it does provides Service ServiceGrounding ServiceModel Supports: How to access it DAML-S describedBy:How it works Grenoble Ecole de Management MEDFORIST Workshop

  11. How do we define and use service semantics? • There are two key issues: • Where to store the generic semantics of the services • How to associate the ontology classes with the services advertised? Grenoble Ecole de Management MEDFORIST Workshop

  12. Where to store the service ontologies? • UDDI does not provide an internal mechanism to store generic service semantics • ebXML, on the other hand, through its classification hierarchy mechanism allows domain specific ontologies to be stored in the registries Grenoble Ecole de Management MEDFORIST Workshop

  13. DAML-S ServiceProfile Class Some of the properties of ServiceProfile class are: • parameter property • For example, a subproperty is input, another output • serviceParameters, subproperties of which may be max response time, geographicRadius, … • serviceType, high level classification of service such as B2B or B2C • serviceCategory, refers to an ontology of services • And more… Grenoble Ecole de Management MEDFORIST Workshop

  14. DAML-S • Provides an upper ontology, that is, defines a class called Service • It is necessary to define the lower levels, i.e, domain specific ontologies • Grounding them in upper ontologies like DAML-S makes them • more consistent and • interoperable Grenoble Ecole de Management MEDFORIST Workshop

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