A. Dogac Grenoble Ecole de Management MEDFORIST Workshop1 Semantics of Web Services Asuman Dogac Middle East Technical University Software R&D Center Ankara, Türkiye

A. Dogac Grenoble Ecole de Management MEDFORIST Workshop 2/14 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

A. Dogac Grenoble Ecole de Management MEDFORIST Workshop 3/14 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

A. Dogac Grenoble Ecole de Management MEDFORIST Workshop 4/14 WSDL does not describe Web service semantics Web ServiceService Consumer Web Service Description defines Semantic description of the properties of a service in DAML-S uses

A. Dogac Grenoble Ecole de Management MEDFORIST Workshop 5/14 Taxonomies are not enough to define service semantics: An Example Taxonomy: UNSPSC Communications and Computer Equipment and Peripherals and Components and Supplies Business Transaction and Personal Business Software Tax Preparation Software

A. Dogac Grenoble Ecole de Management MEDFORIST Workshop 6/14 An Example Ontology for Travel Domain TravelService Entertainment Service Accommodation Service ReserveAFlightBuyATicket AirTransportation Transportation Service

A. Dogac Grenoble Ecole de Management MEDFORIST Workshop 7/14 Properties of ReserveAFlight Generic Service ReserveAFlight originatingFrom destinationTopaymentMethod MyService How to relate MyService to a generic service class?

A. Dogac Grenoble Ecole de Management MEDFORIST Workshop 8/14 Ontology Languages Resource Description Framework DAML+OIL by  DARPA and  On-To-Knowledge project (European Commission, IST ) 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

A. Dogac Grenoble Ecole de Management MEDFORIST Workshop 9/14 Ontology Languages Have formal specification and thus can be queried Provide the means to define sophisticated class properties

A. Dogac Grenoble Ecole de Management MEDFORIST Workshop 10/14 DAML-S describedBy:How it works Service ServiceGrounding ServiceModel ResourceServiceProfile Supports: How to access it presents: What it does provides

A. Dogac Grenoble Ecole de Management MEDFORIST Workshop 11/14 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?

A. Dogac Grenoble Ecole de Management MEDFORIST Workshop 12/14 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

A. Dogac Grenoble Ecole de Management MEDFORIST Workshop 13/14 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…

A. Dogac Grenoble Ecole de Management MEDFORIST Workshop 14/14 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