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Semantic Web services

Semantic Web services. Chankyu Park 08/04/2005. Agenda. Next Generation Web Tutorial of Ontology for SWS Concept of SWS OWL-S ontology OWL-S Development Tools Other efforts to SWS. Next Generation Web. Two interwoven aspects: Program: Web Services Data: Semantic Web.

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Semantic Web services

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  1. Semantic Web services Chankyu Park 08/04/2005

  2. Agenda • Next Generation Web • Tutorial of Ontology for SWS • Concept of SWS • OWL-S ontology • OWL-S Development Tools • Other efforts to SWS

  3. Next Generation Web Two interwoven aspects: Program: Web Services Data: Semantic Web Semantic Web Services Semantic Web Techniques Web Services Techniques API’s on Web (WSDL, SOAP) Automated Knowledge Bases Rules (RuleML) Ontologies (OWL) Databases (SQL, XQuery, RDF) XML First Generation Web

  4. SWSI Language effort,on top of Current WS Standards Stack Wire Protocol Service Description , BPML The Semantic Web Services Initiative (SWSI) is an ad hoc initiative of academic and industrial researchers, many of which are involved in DARPA and EU funded research projects.

  5. Tutorial of Ontology for SWS • “An ontology is a specification of a conceptualization.” • Ontologies consists of: • Concepts • Relations (between concepts) • Instances (specific, non generic concepts) • Axioms (knowledge using logics) • Used for: • Defining knowledge • Communication • Knowledge reuse • A reasoner can be used to make inferences about concepts in ontologies

  6. Ontology Example concept relationship Shape subClassOf subClassOf Circle Square radius property

  7. OWL • Web Ontology Language • XML-based language for representing ontologies • W3C recommendation • Build on RDF and RDFS

  8. XML representation of OWL <!–- concept --> <owl:Class rdf:ID="Shape"/> <owl:Class rdf:ID="Square"> <rdfs:subClassOf rdf:resource="#Shape"/> </owl:Class> <owl:Class rdf:ID="Circle"> <rdfs:subClassOf rdf:resource="#Shape"/> </owl:Class> <!–- property --> <owl:DatatypeProperty rdf:ID="radius"> <rdfs:domain rdf:resource="#Circle"/> <rdfs:range rdf:resource="&xsd;positiveInteger"/> </owl:DatatypeProperty>

  9. Semantic Web Services • Web services were designed to be loosely coupled and inter-operable • Traditional Web services require a huge amount of human interaction for integration of multiple applications • Because it requires an understanding of data and functions of the involved entities • Semantic Web technologies add annotations to data and functions using ontologies

  10. Semantic Web Services • This helps create a machine processable information which can be used for automated service publication, service discovery, service composition, negotiation and execution as primary goals • In other words: Semantic Web Services = Web Services + Semantic Web Technology

  11. Traditional Web Service Traditional Web Service Input ( name=isbn, type=int) getPrice Input ( name=title, type=String) Input ( name=year, type=int) Output ( name=price, type=float)

  12. Semantic Web Service Operation = Ont#getPrice Semantic Web Service getPrice Functional Ontology Input (name=isbn, type=Ont#ISBN) Input ( name=title, type=Ont#BookTitle) Input(name=year, type=Ont#PrintYear) Domain Ontology Output (name=price, type=Ont#BookPrice) Location=Georgia Category=Book Stores QoS Ontology Supply Time=2 days Availability = 0.9

  13. OWL-S Ontology • OWL-S is an OWL ontology to describe Web services • Formerly called DAML_S by DAML Group • W3C Note • OWL-S leverages on OWL to • Support capability based discovery of Web services • Support automatic composition of Web Services • Support automatic invocation of Web services • OWL-S provides a semantic layer over Web services standards • OWL-S relies on WSDL for Web service invocation (see Grounding) • OWL-s Expands UDDI for Web service discovery (OWL-S/UDDI mapping)

  14. OWL-S Upper Ontology • Capability specification • General features of the Service • Quality of Service • Classification in Service • taxonomies • Mapping to WSDL • communication protocol (RPC, HTTP, …) • marshalling/serialization • transformation to and from XSD to OWL • Control flow of the service • Black/Grey/Glass Box view • Protocol Specification • Abstract Messages

  15. Service Profile (What does it do?) • High-level characterization/summary of a service • “Black box” view: Information needed to find and select a service • IOPE: Inputs, outputs, preconditions, effects • “Binding rules” for inputs, outputs • “Roles” involved • Can employ logical rules • Analogous to procedure header, DB schema

  16. OWL-S IOPEs Example • Input: • ItemDescription (several forms), PriceRange, AcctName, Passwd, CreditCard#, Shipping-address, • Input usage rule: • Exists(Acct) => Defined (CreditCard#, Shipping-Address) • Precondition: • Exists(Acct) | CanCreate(Acct) • Output: • ‘Succeed’ + Receipt | ‘Cancel’ | ‘Fail’ • Effect: • ‘Succeed’ ShippingOrderPlaced

  17. OWL-S Upper Ontology • Capability specification • General features of the Service • Quality of Service • Classification in Service • taxonomies • Mapping to WSDL • communication protocol (RPC, HTTP, …) • marshalling/serialization • transformation to and from XSD to OWL • Control flow of the service • Protocol Specification • Abstract Messages

  18. Service Model (How does it work?) • Interpretable description of service provider’s behavior • Tells service user how and when to interact (read/write messages) • “Glass box” view • Detailed characterization of what it does • Can employ logical rules • Analogous to procedure body (but abstract) • Used for: • Service invocation, planning/composition, interoperation, monitoring

  19. OWL-S Service Model

  20. Composite Process Example Output & Effects • confirmation no. • ... Input & Preconditions • customer name • location • car type • dates • credit card no. • ... www.acmecar.com book car service ? • failure notification • … • customer name • flight numbers • dates • credit card no. • ... • confirmation no. • dates • room type • credit card no. • ... ? • confirmation no. • ... • confirmation no. • ... www.acmeair.com book flight service www.acmehotel.com book hotel service ? ? • failure notification • … • failure notification • errror information • …

  21. OWL-S Upper Ontology • Capability specification • General features of the Service • Quality of Service • Classification in Service • taxonomies • Mapping to WSDL • communication protocol (RPC, HTTP, …) • marshalling/serialization • transformation to and from XSD to OWL • Control flow of the service • Black/Grey/Glass Box view • Protocol Specification • Abstract Messages

  22. OWL-S/WSDL Grounding

  23. Service Grounding (How is it used?) • Implementation-specific • Message formatting, transport mechanisms, protocols, serializations of types • Service Model + Grounding give everything needed for using the service • Examples: HTTP forms, SOAP, KQML, CORBA IDL, OAA ICL, Java RMI

  24. Grounding Example • Transport: Secure HTTP • Protocol: HTTP Forms • Address: https://buybot.congo.com:4040/initsub.htm • Type Serializations • ItemDescription (keywords): Set of DAML literals • PriceRange: pair of monetary units, ISO 5678 • CreditCard: https://transcredit.com/S1.daml#SecureTransferFormat

  25. OWL-S Development Tools • WSDL2OWLS. Available at http://www.daml.ri.cmu.edu/wsdl2owls • OWL-S/UDDI matchmaker Available at • http://www.daml.ri.cmu.edu/matchmaker. • Complete implementation of OWL-S 1.1 API

  26. Other efforts to SWS • Web Service Modeling Framework (WSML)- Web Service Modeling Ontology (WSMO) • Internet Reasoning Service (IRS-II) and (IRS-III) are Semantic Web Services Framework, developed by KMI, • …

  27. References OWL-S • The main repository of papers on OWL-S is at http://www.daml.org/services/owl-s/pub-archive.html • The main source of information on OWL-S is the Web site http://www.daml.org/services/owl-s • W3C reference http://www.w3.org/Submission/OWL-S/

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