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Semantic Web Services

This book explores the evolution and application of semantic web services, including the discovery and composition of web services to achieve complex goals. It covers various approaches and technologies such as OWL-S, WSMO, WSDL-S, SAWSDL, and BPEL4WS.

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Semantic Web Services

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  1. Semantic Web Services Peter Bartalos

  2. Dr. Jorge Cardoso and Dr. Amit Sheth http://dme.uma.pt/jcardoso/Books/Semantic-Web-Services-Processes-and-Applications/

  3. Semantic Web • Machine understandable Web content • Not a separate Web but an extension • (semantic) meta-data • RDF, OWL

  4. Web Service “A Web service is a software systemidentifiedby a URI, whose public interfaces andbindings are defined and described usingXML. Its definition can bediscovered byother software systems. These systemsmay then interact with theWeb service in amanner prescribed by its definition, usingXML based messagesconveyed by Internet protocols"

  5. Web Service “A Web service is a software systemidentifiedby a URI, whose public interfaces andbindings are definedand describedusingXML. Its definition can bediscovered byother software systems. These systemsmay then interactwith theWeb service in amanner prescribed by its definition, usingXML based messagesconveyed by Internet protocols"

  6. Semantic Web services • Semantic Web services are the result of the evolution of the syntactic definition of Web services and the semantic Web Bussler et al 2003: A Conceptual Architecture for Semantic Web Enabled Web Services

  7. Semantic Web services • Web services are: • Modular • Self-describing • Self-contained • Accessible over the Internet • Described using WSDL • WSDL - Web Services Description Language • Provide operational information • Does not contain semantic descriptions • It specifies the structure of message components using XML Schema constructs

  8. Semantic Web services • Solution: • Mapping concepts in a Web service description to ontological concepts OWL-S, WSMO, SWSF, WSDL-S, SAWSDL

  9. Semantic Web services • Submissions to the W3C: • OWL-S • WSMO • WSDL-S OWL-S, WSMO, SWSF, WSDL-S, SAWSDL

  10. Semantic Web service discovery • Discovery • The procedure of finding a set of appropriate Web services • Problem • How to efficiently discover Web services • Currently • Universal Description Discovery and Integration (UDDI) • Relatively inefficient • Does not take into account the semantics of Web services Web Service Discovery, Verma et al 2003: MWSDI Downloadable Tool: Lumina - Semantic Web Service Discovery

  11. Semantic Web service discovery • MWSDI • Multiple registries discovery • Ontologies used • Organized registries • Semantic classification • OWL-S based approach • Logic inference is used for matching services • … Web Service Discovery, Verma et al 2003: MWSDI Downloadable Tool: Lumina - Semantic Web Service Discovery

  12. Semantic Web Process • Web Services are application’s functionalities available on the Internet. • Examples: Zip Code, Booking Flights, etc. • Single services has a limited utility • For traveling, it is not sufficient to book a Flight • We must take care about booking the hotel, getting entertained, rental car, etc • Web Services Composition • Collection of services in order to achieve a particular goal

  13. To achieve a given objective – sell my car, I may need more than one Web Service: Car Valuation service – WS1 Car Auction Service – WS2 Online Financial service – WS3 All three WS need to interact seamlessly Problem … To achieve my goal Satya Sanket Sahoo

  14. Semantic Web Process • Web Process • Combine individual services to achieve a more complex goal • Advantage • enables modular design • Implements the control and data flow between services • For example, Service A, B and C. • B is dependent on A’s output message. • A and C can be invoked at the same time OWL-S, WSMO, SWSF, WSDL-S, SAWSDL

  15. Web Services Composition • Necessity to achieve a predetermined goal that cannot be realized by a standalone service • Problem’s Description • Travel Service • Composed of 3 atomic services: Airplane service, Hotel service and Car rental service • The execution order of these 3 tasks is determined by a planner • Proposed Environment involves these phases: • Planning • Discovery • Optimization (Concerns this work) • Execution

  16. Web Services Composition • WS discovery • WS selection • Also non-functional criteria • QoS • Multi-objective optimization approach • WS composition Andrews T. et al. Specification: BPEL4WS - Business Process Execution Language for Web Services - Version 1.1. OWL-S Coalition. OWL-S: Semantic Markup for Web Services.

  17. Web Services Composition • Models to Compose Web Services • BPEL4WS – Business Process Execution Language for Web Services • Abstract and executable processes Andrews T. et al. Specification: BPEL4WS - Business Process Execution Language for Web Services - Version 1.1. OWL-S Coalition. OWL-S: Semantic Markup for Web Services.

  18. Two categories of Web Services Composition: Workflow composition Static workflow composition: EFlow (Casati, Ilnicki, et al. 2000) Dynamic workflow composition: PPM (Polymorphic Process Model) (Schuster, Georgakopoulos, et al. 2000) Web Services Composition

  19. Automatic approaches to WS composition • AI Planning • Golog – Logic Programming Language • Planning Domain Definition Language (PDDL) – action value • Rule-based plan generation – SWORD (Ponnekanti and Fox, 2002) • Hierarchical Task Network (HTN) – SHOP2 (Wu, Sirin, et al. 2003) • Approach considering the user preferences • Software agents

  20. Approaches to WS composition • What about WS composition supported by Collaboration?

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