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The WSMO / L / X Approach. Michael Stollberg DERI – Digital Enterprise Research Institute Alternative Frameworks for Semantics in Web Services: Possibilities for Inclusion in Future Standards SDWP 2005 workshop held at the ICWS 2005, Orlando, Florida, 2005 July 11. WSMO Working Groups.
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The WSMO / L / X Approach Michael Stollberg DERI – Digital Enterprise Research Institute Alternative Frameworks for Semantics in Web Services: Possibilities for Inclusion in Future Standards SDWP 2005 workshop held at the ICWS 2005, Orlando, Florida, 2005 July 11
WSMO Working Groups A Conceptual Model for SWS A Formal Language for WSMO Execution Environment for WSMO A Rule-based Language for SWS W3C Member Submission SDWP 2005 panel, Orlando, Florida (USA), July 2005
Aims & Approach • Semantic Web Services as integrated technology for realizing the vision of the Semantic Web • Current WS technology stack (SOAP, WSDL, UDDI) failed realizing the “Web Service promise” • Ontologies + Semantic Descriptions for automated Web Service Usage • WSMO / L / X = fully fletched framework for Semantic Web Services • Meta-level ontology for semantically describing core elements of Semantic Web Services (WSMO) • well-layered semantic description langauge (WSML) • SWS technologies for automated discovery, composition, conversation, execution • SWS Execution Environment WSMX SDWP 2005 panel, Orlando, Florida (USA), July 2005
Semantic Web Service Technology Aim: automated technologies • Publication: create and publish semantic descriptions • Discovery: detect Web Service capable of resolving a given tasks • Selection: choose most appropriate among available Web Services • Composition: combine services for more complex functionality • Mediation: resolve mismatches (data, protocol, process) between resources that shall interoperate • Execution Support: automated invocation • Monitoring: control the execution process • Compensation: provide transactional support and undo or mitigate unwanted effects • Replacement: facilitate the substitution of services by equivalent ones • Auditing: verify that service execution occurred in the expected way SDWP 2005 panel, Orlando, Florida (USA), July 2005
WSMO Top Level Notions Objectives that a client wants to achieve by using Web Services Provide the formally specified terminology of the information used by all other components Semantic description of Web Services: • Capability (functional) • Interfaces (usage) Connectors between components with mediation facilities for handling heterogeneities Core Elements for Semantic Web Services SDWP 2005 panel, Orlando, Florida (USA), July 2005
WS WS WS WSMO Web Service Description • complete item description • quality aspects • economic aspects • for item management • Advertising of Web Service • Support for WS Discovery Capability functional description Non-functional Properties DC + QoS + Version + financial • realization of functionality by aggregating • other Web Services • functional • decomposition • WS composition • client-service interaction interface for consuming WS • External Visible • Behavior • - Communication • Structure • - ‘Grounding’ Web Service Implementation (not of interest in Web Service Description) Choreography --- Service Interfaces --- Orchestration SDWP 2005 panel, Orlando, Florida (USA), July 2005
OWL and WSML WSML Full OWL Full • reasoning facilities from DL & LP world needed • WSML as well-layered Semantic Web Language First Order Logic full RDF(S) support WSML Rule OWL DL WSML DL WSML Flight Description Logics OWL Lite WSML Core subset Logic Programming SDWP 2005 panel, Orlando, Florida (USA), July 2005
WSMO Service Interface Description Model • common formal model for Service Interface description • ontologies as data model • based on ASMs • not restricted to any executable communication technology • general structure: • Vocabulary Ω: • ontology schema(s) used in service interface description • usage for information interchange: in, out, shared, controlled • States ω(Ω): • a stable status in the information space • defined by attribute values of ontology instances • Guarded Transition GT(ω): • state transition • general structure: if (condition) then (action) • different for Choreography and Orchestration • additional constructs: add, delete, update SDWP 2005 panel, Orlando, Florida (USA), July 2005
WSMX Usage Scenario - P2P SDWP 2005 panel, Orlando, Florida (USA), July 2005
WSMX Architecture SDWP 2005 panel, Orlando, Florida (USA), July 2005
Position • Semantic Web vision / Web Service promise not reachable without semantics • WSMO / L / X as full semantically enabled Web Service techology • demonstration of benefits / added value of semantic technology • Semantic descriptions are complicated to create • Ontology / Knowledge Engineers needed • exhaustive tool support needed for description / implementation creation (“hide semantics from system developers”) • What future standards should contain: • meta-level description structure of SWS core elements (what is described) • semantic description langauge (how it is described) • not restricted to specific technology or implementation design SDWP 2005 panel, Orlando, Florida (USA), July 2005