1. 1 / 20 Semantic Web Services Jun. 2003. Presentation: Y.G. Ha

2. 2 / 20 Preface The original paper “Semantic Web Services” –Proposes the markup of Web services in DAML which enables a wide variety of agent technologies for automated Web services –Written by Sheila A. McIlraith, Tran Cao Son and Honglei Zeng (Stanford Univ.) –Appeared in IEEE Intelligent Systems, Mar. 2001.

3. 3 / 20 Preface (Cont’d) The original paper is out of date … –The markup is being standardized as DAML-S today (currently v0.9b) –Sheila McIlraith is one of the authors of DAML-S –DAML: DARPA Agent Markup Language –DAML-S: DAML Services

4. 4 / 20 Contents Web ontology Semantic Web services –Focused on DAML-S The challenge

5. 5 / 20 Web Ontology Languages XML HTML RDFS SHOE OIL DAML-ONT OWL RDF Revision Extend vocabularies Combine vocabularies Extend HTML tags for semantic description Define vocabularies OWL-S SGML DAML-S This paper For Web services 1992 1998 1999 2000 2001 2002 2003 DAML (DAML+OIL) DAML (DAML+OIL)

6. 6 / 20 Web Ontology Ontology –A knowledge representation Concepts Relationships: is-a, is-part-of, … –Representation scheme Frames, semantic network, logic programs, … Web ontology –Ontology of Web resources Semantic markup to annotate Web resources –Web ontology languages Classes = Concepts Properties = Relations RDF-based –DAML+OIL (DARPA) –OWL (W3C)

7. 7 / 20 A DAML Ontology Example <rdf:RDF xmlns:rdf ="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" xmlns:daml="http://www.daml.org/2001/03/daml+oil#" xmlns:xsd ="http://www.w3.org/2000/10/XMLSchema#" > $Id: daml+oil-ex.daml,v 1.9 $ An example ontology, with data types taken from XML Schema Animal... … 1 … Cain Cain is a person. …

8. 8 / 20 Semantic Web Today’s Web –HTML-based –Tags for presentation layout –For human interpretation –Search HTML pages for a given keyword according to presentation layout Semantic Web –Ontology-based –Annotate Web documents based on Web ontologies –Agent understandable semantics –Using AI technology: reasoning about Web ontologies

9. 9 / 20 Web Service Ontology Ontology of Web services –Define markup for describing Web services –Is a Web ontology Domain-independent ontology (upper ontology) –DAML-S Markup for service profile: What the service does (IOPEs) Markup for service modeling: How it works (process, param., sequence, …) Markup for service grounding: How to access it (protocol, messages, …) Domain-specific ontology –Based on upper ontology –Domain-dependent knowledge on services –Service class “BookSelling” Subclass of “E_Commerce” which is subclass of “Profile” in DAML-S Its detailed profile properties, process modeling and grounding information is also described in DAML-S markup

10. 10 / 20 A BookSelling Service daml:Class service:ServiceProfile profile:Profile profileHierarchy:Information_ServiceprofileHierarchy:E_Commerce profileHierarchy:BookSellingprofileHierarchy:AirlineTicketing congoProfile:Profile_Congo_BookBuying_Service

11. 11 / 20 A BookSelling Service Profile <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" xmlns:daml="http://www.daml.org/2001/03/daml+oil#" xmlns:service="http://www.daml.org/services/daml-s/0.9/Service.daml#" xmlns:process="http://www.daml.org/services/daml-s/0.9/Process.daml#" xmlns:profile="http://www.daml.org/services/daml-s/0.9/Profile.daml#" xmlns:profileHierarchy="http://www.daml.org/services/daml- s/0.9/ProfileHierarchy.daml#" xmlns:xsd="http://www.w3.org/2001/XMLSchema.xsd#" xmlns:congoService="http://www.daml.org/services/daml- s/0.9/CongoService.daml#" xmlns:congoProcess="http://www.daml.org/services/daml- s/0.9/CongoProcess.daml#“ xmlns="http://www.daml.org/services/daml-s/0.9/CongoProfile.daml#"> $Id: CongoProfile.daml,v 1.21 $ DAML-S Coalition: CongoBuy Example for DAML-S release 0.9 Congo_BookBuying_Agent This agentified service provides the opportunity to browse a book selling site and buy books there ExpressCongoBuy 412 268 8780 Bravo@Bravoair.com somewhere 2, OnWeb, Montana 52321, USA http://www.daml.org/services/daml- s/0.9/ExpressCongoBuy.html … bookTitle … EReceipt … AcctExists … BuyEffectType

12. 12 / 20 Semantic Web Service Today’s Web service –Communication-level description of how it is being sent (messages and protocols using XML) –Focused on improving service discovery and execution –Standards like UDDI, SOAP, WSDL and ebXML –Microsoft.NET, SUN ONE, … Semantic Web service –Semantic-level description of what is being sent based on Web service ontology: richer level of description –More sophisticated interactions and reasoning at the agent or application level –Automated Web services including automatic service composition and interoperation

13. 13 / 20 Semantic Web Service Framework Upper ontology like DAML-S Domain-specific ontologies Distributed KB of services Reason about Web services

14. 14 / 20 Automatic Service Discovery Locating Web services providing a particular service with requested properties –“Find a service that sells airline tickets between San Francisco and Toronto and that accepts payment by Diner’s Club credit card” Today’s Web service –The user must perform this task by using search engine and navigating discovered sites Semantic Web service –Necessary information is specified as semantic markup –An agent or ontology-enabled search engine does the task DAML-S markup for service discovery –profile:serviceName, profile:textDescription, profile:serviceCategory, profile:webURL, profile:physicalAddress, profile:input, profile:output, profile:precondition, profile:effect, …

15. 15 / 20 Automatic Service Execution Automatically invoking an identified Web service –“Buy me an airline ticket from www.acmetravel.com on UAL Flight 1234 from San Francisco to Toronto on 3 March” Today’s Web service –The user must go to the Web site, fill out a form and click a button to execute the service –Or might send an http request directly to the service URL with the appropriate parameters encoded Semantic Web service –The markup tells the agent what input is necessary, what information will be returned, and how to execute DAML-S markup for service execution –process:input, process:output, process:precondition, process:effect, process:Iterate, process:Sequence, process:If-Then-Else, …

16. 16 / 20 Automatic Service Composition Automatic selection, composition, and interoperation of appropriate Web services to perform a task Given a high-level description of the task’s objective –“Make the travel arrangements for my IJCAI 2001 conference trip” Today’s Web service –The user must select the Web services, manually specify the composition, and provide the input at choice points Semantic Web service –The information necessary to select, compose and respond to services is encoded at the service Web sites as semantic markup –An agent manipulates this markup together with a specification of the task’s objectives and user’s preferences, to achieve the task automatically DAML-S markup for service composition –process:AtomicProcess, process:SimpleProcess, process:CompositeProcess, process:input, process:output, process:precondition, process:effect, process:whileProcess, process:Sequence, process:Parallel, process:If-Then-Else, …

17. 17 / 20 Ontology Is Not Enough How to represent constraints or preferences –Constraints are in forms of rules –Such as “Teenager(?X)  AgeOf(?X) ≥ 10 ∧ AgeOf(?X) < 20” DAML(OWL) is based on DL(Description Logic) –DL is suitable to represent network of concepts but not rules Need rules layer on top of ontology –Rules provide more compelling syntax and further expressive power for non-classification oriented information (eg. service process modeling) –Tradeoff: expressive power vs. tractability

18. 18 / 20 DAML-Rules Markup for rules –Based on DAML –Formerly known as DAML-L –Based on another logic system HL (Horn Logic) –Current status RuleML as point of departure? Still on discussion …

19. 19 / 20 Wrapping Up UnicodeURI XML + NS + XML Schema RDF + RDF Schema DAML+OIL Semantic Web Stack Domain-specific Service Ontology DAML-RulesDAML-S Agents Semantic Web Service Stack Automatic Service Discovery Automatic Service Execution Automatic Service Composition

20. 20 / 20 References DAML family –http://www.daml.org/2001/03/daml+oil-index.htmlhttp://www.daml.org/2001/03/daml+oil-index.html –http://www.daml.org/services/http://www.daml.org/services/ –http://www.daml.org/rules/http://www.daml.org/rules/ Web ontology & semantic Web –http://www.w3.org/2001/sw/http://www.w3.org/2001/sw/ –http://www.w3.org/2001/sw/WebOnt/http://www.w3.org/2001/sw/WebOnt/ Web services –http://www.w3.org/2002/ws/http://www.w3.org/2002/ws/ –http://www.ebxml.orghttp://www.ebxml.org –http://www.uddi.orghttp://www.uddi.org RuleML initiative –http://www.ruleml.orghttp://www.ruleml.org