1. Introduction to Semantic Web Portal Ching-Long Yeh 葉慶隆 Department of Computer Science and Engineering Tatung University chingyeh@cse.ttu.edu.tw http://www.cse.ttu.edu.tw/chingyeh

2. EB & SWS2 Content Background XML, XML Protocol and Web Services EB Standard: RosettaNet EB Standard: ebXML Semantic Web: Machine Processable Web Ontology Basics XML-based Ontology Languages: RDFS, DAML, OWL DAML-S: an Ontology for Semantic Web Services Semantic Web Portals Conclusions

3. EB & SWS3 Background WWW –HTML –HTTP –Mainly man-machine interaction Electronic Business (EB) –Standard XML document –XML Protocol –AP-2-AP interaction Semantic Web Services –RDF –Ontology –Web Services, agents

4. EB & SWS4 What is XML? Extensible Markup Language A Syntax for Documents A Meta-Markup Language A Structural and Semantic Language, not a Formatting Language Not just for Web pages

5. EB & SWS5 XML Standards DTD Namespace Schema DOM CSS, XSL-T, XSL-FO XLink XPointer

6. EB & SWS6 XML Protocol: SOAP

7. EB & SWS7 <SOAP:Encelope xmlns:SOAP=http://schemas.xmlsoap.org/soap/envelope xmlns=“http://www.smallco.org/order” xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance”> SterlingVommerce SmallCo Purchase Order bbc006751 Small Co Enterprise 123456789-0456 John Adams 214-340-1234 … … A SOAP Message

8. EB & SWS8 Web Services

9. EB & SWS9 Introduction to Semantic Web Facilities to put machine-understandable data on the Web are becoming a high priority for many communities. The Web can reach its full potential only if it becomes a place where data can be shared and processed by automated tools as well as by people. For the Web to scale, tomorrow's programs must be able to share and process data even when these programs have been designed totally independently.

10. EB & SWS10 Introduction to Semantic Web The Semantic Web is a vision: See “W3C Semantic Web Activity,” by Marja-Riitta Koivunen, for more descriptions.W3C Semantic Web Activity the idea of having data on the web defined and linked in a way that it can be used by machines not just for display purposes, but for automation, integration and reuse of data across various applications

11. EB & SWS11 The Semantic Web Layered Architecture (http://www.w3.org/2001/T alks/0228-tbl/slide5-0.html) Tim Berners-Lee: “Axioms, Architecture and Aspirations” W3C all-working group plenary Meeting 28 February 2001 URIUnicode XMLNamespaces XML Schema Sig RDF M&S RDF Schema Ontology Rules Logic Proof Trust

12. EB & SWS12 The Big Picture of SW

13. Ontology Basics

14. EB & SWS14 Why Develop an Ontology Reasons why developing an ontology: –To share common understanding of the structure of information among people or software agents –To enable reuse of domain knowledge –To make domain assumptions explicit –To separate domain knowledge from the operational knowledge –To analyze domain knowledge

15. EB & SWS15 Ontologies One widely cited definition of an ontology is Gruber’s [Gruber 1993] “A specification of a conceptualization”.

16. EB & SWS16 Ontologies Ontologies can be used to provide a concrete specification of term names and term meanings.

17. EB & SWS17 What Is in an Ontology? For the purposes of this guide an ontology is a formal explicit description of –concepts in a domain of discourse (classes (sometimes called concepts)), –properties of each concept describing various features and attributes of the concept (slots (sometimes called roles or properties)), and –restrictions on slots (facets (sometimes called role restrictions)). An ontology together with a set of individual instances of classes constitutes a knowledge base.

18. EB & SWS18 A Simple Knowledge-Engineering Methodology There is no one “correct” way or methodology for developing ontologies. Here we discuss general issues to consider and offer one possible process for developing an ontology.

19. EB & SWS19 A Simple Knowledge-Engineering Methodology Step 1: Determine the domain and scope of the ontology Step 2: Consider reusing existing ontologies Step 3: Enumerate important terms in the ontology Step 4: Define the classes and the class hierarchy Step 5: Define the properties of classes—slots Step 6: Define the facets of the slots Step 7: Create instances

20. EB & SWS20 Uses Cases of Web Ontologies Web portal Multimedia collections Corporate web site management Design documentation Agents and services Ubiquitous computing

21. XML-Based Ontology Languages

22. EB & SWS22 RDF M&S RDF (Resource Description Framework) –Beyond Machine readable to Machine understandable RDF consists of two parts –RDF Model (a set of triples) –RDF Syntax (different XML serialization syntaxes) RDF Schema for definition of Vocabularies (simple Ontologies) for RDF (and in RDF)

23. EB & SWS23 RDF Data Model Resources –A resource is a thing you talk about (can reference) –Resources have URI’s –RDF definitions are themselves Resources (linkage, see requirement 1) Properties –slots, define relationships to other resources or atomic values Statements –“ Resource has Property with Value ” –(Values can be resources or atomic XML data) Similar to Frame Systems

24. EB & SWS24 A Simple Example Statement –“Ora Lassila is the creator of the resource http://www.w3.org/Home/Lassila ” Structure –Resource(subject) http://www.w3.org/Home/Lassila –Property(predicate) http://www.schema.org/#Creator –Value(object) "Ora Lassila” Directed graph http://www.w3.org/Home/Lassila s:Creator Ora Lassila

25. EB & SWS25 EmailName s:Creator http://www.w3.org/Home/Lassila Another Example To add properties to Creator, point through an intermediate Resource. Person://fi/654645635 Ora Lassila lassila@w3.org

26. EB & SWS26 Example: Bag The students in course 6.001 are Amy, Tim, John, Mary, and Sue Rdf:Bag /Students/Amy /Students/Tim /Students/John /Students/Mary /Students/Sue bagid1 /courses/6.001 students rdf:type rdf:_1 rdf:_2 rdf:_3 rdf:_4 rdf:_5

27. EB & SWS27 rdf:_1 rdf:_2 rdf:_3 rdf:type source ftp.eu.net ftp.cs.purdue.edu ftp.x.org Example: Alternative The source code for X11 may be found at ftp.x.org, ftp.cs.purdue.edu, or ftp.eu.net altid rdf:Alt http://x.org/package/X11

28. EB & SWS28 RDF Syntax I Data model does not enforce particular syntax Specification suggests many different syntaxes based on XML General form: Ora Lassila Starts an RDF-Description Properties Subject (OID) Literal Resource (possibly another RDF-description)

29. EB & SWS29 Resulting Graph Ora Lassila http://www.w3c.org/amaya http://www.w3.org/Home/Lassila Ora Lassila s:createdWith s:Creator

30. EB & SWS30 RDF Syntax II: Syntactic Varieties <s:Homepage rdf:about="http://www.w3.org/Home/Lassila” s:Creator=“Ora Lassila”/> Typing Information In-Element Property Property Subject (OID) http://www.w3c.org/amaya http://www.w3.org/Home/Lassila Ora Lassila s:createdWith s:Creator HTMLEditor s:Homepage rdf:type

31. EB & SWS31 RDF Schema (RDFS) RDF just defines the data model Need for definition of vocabularies for the data model - an Ontology Language! The RDF Schema mechanism provides a basic type system for use in RDF models. The RDF schema specification language is less expressive, but much simpler to implement, than full predicate calculus languages such as CycL and KIF.

32. EB & SWS32 Most Important Modeling Primitives Core Classes –Root-Class rdfs:Resource –MetaClass rdfs:Class –Literals rdfs:Literal rdfs:subclassOf -property Inherited from RDF: properties (slots) rdfs:domain & rdfs:range rdfs:label, rdfs:comment, etc. Inherited from RDF: InstanceOf ( rdf:type )

33. EB & SWS33 DAML+OIL: an Ontology Language Extension of RDF Schema Ontology Language DAML+OIL: Result of a Joint (European + US-American) Committee Extension of RDF Schema –Class Expressions (Intersection, Union, Complement) –XML Schema Datatypes –Enumerations –Property Restrictions Cardinality Constraints Value Restrictions

34. EB & SWS34 OWL W3C Web Ontology Language OWL provides three increasingly expressive sublanguages: OWL Lite, OWL DL, and OWL Full.

35. EB & SWS35 OWL W3C Web Ontology Language OWL Lite language constructs RDF Schema Features: Class rdf:Property rdfs:subClassOf rdfs:subPropertyOf rdfs:domain rdfs:range Individual (In)Equality: equivalentClass equivalentProperty sameAs differentFrom allDifferent Property Characteristics: inverseOf TransitiveProperty SymmetricProperty FunctionalProperty InverseFunctionalProperty Property Type Restrictions: allValuesFrom someValuesFrom Restricted Cardinality: minCardinality (only 0 or 1) maxCardinality (only 0 or 1) cardinality (only 0 or 1) Header Information: ontology imports

36. DAML-S: An Ontology for Semantic web Service

37. EB & SWS37 DAML-S Users and software agents should be able to discover, invoke, compose, and monitor Web resources offering particular services and having particular properties. As part of the DARPA Agent Markup Language program, we have begun to develop an ontology of services, called DAML-S.

38. EB & SWS38 Top Level of the Service Ontology Service Resource Service Grounding ServiceProfile ServiceModel provides presents supportsdescribed by (what it does) (how it works) (how to access it)

39. EB & SWS39 Process Modeling Ontology

40. Semantic Web Portal

41. EB & SWS41 Web Portals A web portal is a web site that provides information content on a common topic. –General portals, e.g., Yahoo, Excite, Netscape, Lycos, CNET, MSN, and AOL.com –Specialized portal e.g., gardeners.com, semanticweb.org Making valuable information to be found –directory service, –search facility –news, e-mail, –community forum

42. KA2 An Ontology-Based Community Web Portal

43. EB & SWS43 Ontology-Based Web Portals Ontology represents –common knowledge and interests sharing within their community Tasks that ontology can be used to support a portal –Accessing a portal Conceptual search and navigation Inference capabilities –Providing information Methods and tools accounting for the diversity of information sources

44. EB & SWS44 KA2 Knowledge Annotation Initiative of the Knowledge Acquisition Community The basic scenario –WWW documents of the KS community were annotated according to the schema of an ontology. –The annotations enable intelligent access to these documents and infer implicit knowledge from explicitly stated facts and rules from the ontology.

45. EB & SWS45 The KA2 Ontology Class hierarchy Person Employee Academic-Staff Lecturer Researcher Administrative-Staff Secretary Technical-Staff Student Phd-Student Relations Address, Affiliation, Cooperates-With, Editor-Of,Email, First-Name, Has- Publication, Head-Of-Group, Head-Of- Project, Last-Name, Member-Of- Organization, Member-Of-Program- Committee, Member-Of-Research-Group, Middle-Initial, Organizer-Of-Chair-Of, Person-Name, Photo, Research-Interest, Secretary-Of, Studies-At, Supervises, Supervisor, Works-At-Project Person-ontology Class hierarchy On-Line-Publication Publication Article Article-In-Book Conference-Paper Journal-Article Technical-Report Workshop-Paper Book Journal IEEE-Expert IJHCS Special-Issue Relations Abstract, Book-Editor, Conference- Proceedings-Title, Contains-Article-In- Book, Contains-Article-In-Journal, Describes-Project, First-Page, Has- Author, Has-Publisher, In-Book, In- Conference, In-Journal, In-Organization, In-Workshop, Journal-Editor, Journal- Number, Journal-Publisher, Journal-Year, Last-Page, On-Line-Version, … Publication-ontology

46. EB & SWS46 Accessing the Community Web Portal Query capability –In F-Logic mechanism Navigating capability –As the easy-to-use front-end of the query mechanism

47. EB & SWS47 Development of Web Portals

48. EB & SWS48 The System Architecture

49. EB & SWS49 What is Sesame ? Sesame is RDF Schema-based repository and querying facility that offers: persistent storage of RDF data export of repository contents in RDF format data administration functionality query engine (RQL, SeRQL)

50. EB & SWS50 Sesame’s Architecture

51. An Ontology-Based Portal for Digital Library Services

52. System Architect ure

53. Translator ( RDF To FLEX)

54. Ontology-Based Web Portal(1/2)

55. Ontology-Based Web Portal(2/2)

56. Annotation Tool

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62. Current work(2/3)

63. EB & SWS63 Conclusions New web technologies –XML –Electronic Business –Semantic Web (Services) Integration of existing technologies to create new one