Semantic Web Services Sheila A. McIlraith, Tran Cao Son, and Honglei Zeng Stanford University 2001

1. Semantic Web ServicesSheila A. McIlraith, Tran Cao Son, and Honglei ZengStanford University2001 Presenter: Ali Fatolahi CSI 5389 Winter 2006 www.site.uottawa.ca/~afato092

2. The Problem • Web • Toward service provider • Computers • Moving inside devices • Web usage • Getting automated • Web Page Change • Needs an API Change www.site.uottawa.ca/~afato092

3. The Solution • Web Services need to be • Computer-Interpretable • Use-Apparent • Agent-Ready • Semantic Web Service is a Web Service • Unambiguous and Machine-Understandable • Properties, Capabilities, Interfaces, and Effects www.site.uottawa.ca/~afato092

4. Realization • AI-Inspired Content Markup Languages • Ontology Interface Layer (OIL1) • DARPA Agent Markup Language (DAML2) • DAML +OIL3 • DAML –L4 • Still in Progress www.site.uottawa.ca/~afato092

5. Approach of This Paper • An Agent-Independent Declarative API • Data and Metadata • Properties and Capabilities • Interface for Execution • Prerequisites and Consequences • Semantic Markup Exploiting Ontology • DAML Family • Distributed Knowledgebase (KB) www.site.uottawa.ca/~afato092

6. Role of the Distributed KB • Enabling Agents to Perform Automatic • Discovery • Execution • Composition and Interoperation • A Means for Agents to • Populate their Local KBs • Reason about Web Services www.site.uottawa.ca/~afato092

7. The Manual Web Service Usage • Use a search engine to find a service • Either read the web page associated with that service or execute the service • Fill out the forms and click the button • Inform the user about possible compositions • Interact with the user step by step • … www.site.uottawa.ca/~afato092

8. The Automatic Web Service Usage • User just defines her objectives • An agent does everything using • WS Descriptions on WS Sites • Ontology-Enhanced Search Engines • Main Tasks in Automatic Mood • Discovery • Execution • Composition and Interoperation www.site.uottawa.ca/~afato092

9. Automatic Discovery • Automatically Locating Web Services • Given Particular Service and Its Properties • Semantic Markup at the Web Sites • To Specify the Service • How to Find? • Service Registry • (Ontology-Enhanced) Search Engine www.site.uottawa.ca/~afato092

10. Automatic Execution • Automatically Executing a Web Service • By a Computer Program or Agent • Semantic Markup of Web Services • A Declarative, Computer-Interpretable API for Executing Services • Tells the Agent What Input Is Necessary • What Information Will Be Returned • How to Execute and Interact With the Service www.site.uottawa.ca/~afato092

11. Automatic Composition and Interoperation • Automatic • Selection • Composition • Interoperation • Given a High-Level Description of the Objective • Semantic Markup of Web Services • A software can manipulate this markup • Specification of the Objectives, Constraints, … www.site.uottawa.ca/~afato092

12. State of the art • Today they are not automatic • Lack of Content Markup and a Suitable Markup Language • Academic Research • Agent matchmaking research (Lark5) • XML-based standards in industry • UDDI, WSDL, ebXML, … www.site.uottawa.ca/~afato092

13. What distinguishes this paper? • Expressive Semantic Web Markup Language • Well-Defined Semantics • A Semantic Layer • Sitting On Top of WSDL • A Richer Level of Description • More Sophisticated Interactions • Reasoning www.site.uottawa.ca/~afato092

14. Markup Strategy • Markup Subjects • Web Services • User and Group Constraints and Preferences • Agent Procedures • Markup Tool • DAML Ontology • Sharing Common Concepts • Specification and Reuse • Concept Mapping • Composition of New Concepts www.site.uottawa.ca/~afato092

15. Ontology An Example Domain-Independent Service N includes 1 Primitive Service Complex Service Domain-Specific Buy Origin Destination Departure Date Customer Buy Ticket Buy Movie Ticket Buy Airline Ticket www.site.uottawa.ca/~afato092

16. WS Discovery Markup • Associates properties with services • Relevant to Classification and Selection • Example: BuyUALTicket Service • Service-Independent Property Types • Company Name, The Service URL, Unique Service Identifier, The Intended Use, … • Service-Specific Property Types • Valid Methods of Payment, Travel Bonus Plans Accepted, … www.site.uottawa.ca/~afato092

17. WS Execution Markup • Requires a dataflow model • Function Metaphor • Process or Conversation Model • It must enable the agent to • automatically construct and execute a Web service request • interpret and potentially respond to the service’s response. www.site.uottawa.ca/~afato092

18. WS Composition Markup • AI-Based action metaphor • Plan Domain Description Language (PDDL6) • Parameters, Preconditions and Effects • Defines Consequences of WS Execution • Buying a Book • Credit Card will be debited • Each WS is conceived as an action • PDDL translation to AI action already exists www.site.uottawa.ca/~afato092

19. Constraints and Preferences Markup • Bob Prefers to Drive if • Travel time is less than 3 hours • His company mandates him to • Travel by American Airlines • Markup Language: DAML-L • Agent Usage is more challenging than the Markup itself. www.site.uottawa.ca/~afato092

20. Agent Technology • Model-Based Programming • Comprises a Model • The Agent’s KB • And a Program • The generic procedure we wish to execute • Agent Programming Language Golog • Congolog • Situation Calculus • Open Agent Architecture (OAA7) sends requests www.site.uottawa.ca/~afato092

21. How it works? • User requests a generic procedure • Agent populates its local KB • adds the user’s constraints to its KB • provides a logical encoding of the preconditions and effects of the Web service actions • ConGolog instantiates user request into • a sequence of primitive actions • Agent finds appropriate service for each action • … www.site.uottawa.ca/~afato092

22. Assessment • There is no sample of: • Situation Calculus • ConGolog • Semantic Markup • … • We just see the screen shots and general terms • But it’s a promising work! www.site.uottawa.ca/~afato092

23. What’s up today? • Based on • J. Nandigam et al. “Semantic Web Services”.2005. [8] • People still trying out • Languages • Environments • Frameworks • Ontologies www.site.uottawa.ca/~afato092

24. Some Ideas • What about WSFL? • For Procedures • Agent-Mediated Semantic WS Technology • Both the Good and the Bad • Semantic Web without Agents?! • Do not interrupt user please! • Opportunity for Agent Technology • Threat for Semantic Web Service www.site.uottawa.ca/~afato092

25. Thank You, Any Question? ? www.site.uottawa.ca/~afato092

26. References • F. van Harmelen and I. Horrocks, “FAQs on OIL: The Ontology Inference Layer,” IEEE Intelligent Systems, vol. 15, no. 6, Nov./Dec. 2000, pp. 69–72. • J. Hendler and D. McGuinness, “The DARPA Agent Markup Language,” IEEE Intelligent Systems, vol. 15, no. 6,Nov./Dec. 2000, pp. 72–73. • www.daml.org/2000/10/daml-oil • www.daml.org/2001/03/daml+oil-index.html • Somewhere in www.stanford.edu! • K. Sycara et al., “Dynamic Service Matchmaking among Agents in Open Information Environments,” J. ACM SIGMOD Record, vol. 28, no. 1, Mar. 1999, pp. 47–53. • M. Ghallab et al., PDDL: The Planning Domain Definition Language, Version 1.2, tech. report CVC TR–98–003/DCS TR–1165, Yale Center for Computational Vision and Control,Yale Univ.,New Haven, Conn., 1998. • D.L. Martin, A.J. Cheyer, and D.B. Moran, “The Open Agent Architecture: A Framework for Building Distributed Software Systems,” Applied Artificial Intelligence, vol. 13, nos. 1–2, Jan.–Mar. 1999, pp. 91–128. • Jagadeesh Nandigam, Venkat N Gudivada and Mrunalini Kalavala. “SEMANTIC WEB SERVICES” Proceedings of the CCSC: Midwestern Conference, JCSC 21, 1 (October 2005). pp. 50-63. www.site.uottawa.ca/~afato092