1. Markup Languages in Semantic Web and Research of Semantic Web at Tatung Univ. 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. Semantic Web Research at Tatung2 Outline Introduction to the Semantic Web Some Markup Languages in the Semantic Web –RDF(S) –DAML(-S) The Big Picture of the Semantic Web An Architecture of RDF Triple Data Store –An RDF Parser in Prolog –The Repository storage –APIs and User Interface Semantic Community Portal Conclusions

3. Semantic Web Research at Tatung3 Sources Part of the slides are selected from the following sources: –Knowledge Markup and Resource Semantics, By Harold Boley, Stefan Decker, and Michael Sintek, IJCAI-01 Tutorial, http://www.ijcai-01.org/ –Anupriya Ankolenkar, et al., “DAML-S: Semantic Markup For Web Services,”, Proceedings of SWWS’ 01, the First Semantic Web Working Symposium, California, USA, July 30 - August 1, 2001.

4. Semantic Web Research at Tatung4 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.

5. Semantic Web Research at Tatung5 Introduction to Semantic Web The Semantic Web is a vision: 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. See “W3C Semantic Web Activity,” by Marja-Riitta Koivunen, for more descriptions.W3C Semantic Web Activity

6. Semantic Web Research at Tatung6 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

7. Semantic Web Research at Tatung7 AI’s Chance Increasing demand for formalized knowledge on the Web: AI’s chance! XML- & RDF-based markup languages provide a 'universal' storage/interchange format for such Web- distributed knowledge representation. DTDs XML RDF[S] Namespaces Stylesheets CSS XSLT XQL Queries XML-QL Transformations Acquisition Protégé Agents Frames Rules SHOE HornML RuleML DAML XQuery TopicMaps Ontobroker

8. Introduction to RDF RDF (Resource Description Framework) –Beyond Machine readable to Machine understandable RDF unites a wide variety of stakeholders: –Digital librarians, content-raters, privacy advocates, B2B industries, AI... –Significant (but less than XML) industrial momentum, lead by W3C 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) Knowledge Markup and Resource Semantics, By Harold Boley, Stefan Decker, and Michael Sintek, IJCAI-01 Tutorial, http://www.ijcai-01.org/

9. Semantic Web Research at Tatung9 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

10. Semantic Web Research at Tatung10 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

11. Semantic Web Research at Tatung11 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

12. Semantic Web Research at Tatung12 Collection Containers Multiple occurrences of the same PropertyType don’t establish a relation between the values –The Millers own a boat, a bike, and a TV set –The Millers need (a car or a truck) –(Sarah and Bob) bought a new car RDF defines three special Resources : –Bag unordered valuesrdf:Bag –Sequence ordered valuesrdf:Seq –Alternative single valuerdf:Alt Core RDF does not enforce ‘set’ semantics amongst values

13. Semantic Web Research at Tatung13 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

14. Semantic Web Research at Tatung14 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

15. Semantic Web Research at Tatung15 Statements About Statements Making statements about statements requires a process for transforming them into Resources –subject the original resource –predicatethe original property –objectthe original value –typerdf:Statement

16. Semantic Web Research at Tatung16 Statements About Statements Ralph Swick says that Ora Lassila is the creator of the resource http://www.w3.org/Home/Lassila. <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:a="http://description.org/schema/"> Ora Lassila Ralph Swick

17. Semantic Web Research at Tatung17 http://www.w3.org/Home/Lassila rdf:Statement s:Creator Ora Lasilla Ralph Swick rdf:object rdf:predicate a:attributedTo rdf:type rdf:subject Representation of a reified statement

18. Semantic Web Research at Tatung18 Statements About Statements Ora Lassila Ora's Home Page Ralph Swick

19. Semantic Web Research at Tatung19 A Formal Model of RDF RDF itself is mathematically straightforward: –Basic Definitions Resources. Properties  Resources Literals Statements = Properties  Resources  {Resources  Literals} –Typing rdf:type  Properties {RDF:type, sub, obj}  Statements  obj  Resources –for triples like {p,r1,r2} the RDF spec should use some different bracketing, like (p,r1,r2)

20. Semantic Web Research at Tatung20 Formal Model of RDF II –Reification rdf:Statement  Resource-Properties {rdf:predicate, rdf:subject, rdf:object }  Properties Reification of a triple {pred, sub, obj} of Statements is an element r of Resources representing the reified triple and the elements s1, s2, s3, and s4 of Statements such that –s1: {RDF:predicate, r, pred} –s2: {RDF:subject, r, sub} –s3: {RDF:object, r, obj} –s4: {RDF:type, r, [RDF:Statement]} –Collections { RDF:Seq, RDF:Bag, and RDF:Alt }  Resources-Properties There is a subset of Properties corresponding to the ordinals (1, 2, 3,...) called Ord. We refer to elements of Ord as RDF:_1, RDF:_2, RDF:_3,...

21. Semantic Web Research at Tatung21 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)

22. Semantic Web Research at Tatung22 Resulting Graph Ora Lassila http://www.w3c.org/amaya http://www.w3.org/Home/Lassila Ora Lassila s:createdWith s:Creator

23. 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

24. RDF Schema

25. Semantic Web Research at Tatung25 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.

26. Semantic Web Research at Tatung26 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 )

27. Classes and Properties Resources Classes Property ConstraintProperty rdf:type rdfs:subClassOf rdfs:subPropertyOf rdfs:comment rdfs:label rdfs:seeAlso rdfs:isDefinedBy rdfs:domain rdfs:range rdfs:Resource rdfs:Class rdf:Property rdfs:ConstraintProperty rdfs:Literal Classes and Resources as Sets and Elements

28. DARPA Agent Markup Language DAML

29. Semantic Web Research at Tatung29 DARPA Agent Markup Language Program DARPA funded Research Program (also funded the Development of the ARPANNET -> Internet) Focusing on building the foundation for the Semantic Web: http://www.daml.org Ontology Language DAML+OIL: Result of a Joint (European + US-American) Committee Rule Language in preparation

30. Semantic Web Research at Tatung30 DAML+OIL 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

31. Semantic Web Research at Tatung31 Example: Intersection & Synonyms

32. Semantic Web Research at Tatung32 Example: Disjoint & Complement no car is a person Disjoint not strictly necessary, since expressible via pairwise subClassOf of complementOf, as for Car and Person :

33. Semantic Web Research at Tatung33 Example: Properties (Transitive, Inverse, subProperty, UniqueProperty, range, Datatypes)

34. Semantic Web Research at Tatung34 Using User-defined Datatypes (based on XML Schema) =18-->

35. Semantic Web Research at Tatung35 Instances (Individuals) Adam Adam is a person....

36. Semantic Web Services Source: Anupriya Ankolenkar, et al., “ DAML-S: Semantic Markup For Web Services,”, Proceedings of SWWS’ 01, the First Semantic Web Working Symposium, California, USA, July 30 - August 1, 2001

37. Semantic Web Research at Tatung37 Web Services

38. Semantic Web Research at Tatung38 What Is 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.

39. Semantic Web Research at Tatung39 Some Motivating Tasks Automatic Web service discovery Automatic Web service invocation Automatic Web service composition and interoperation Automatic Web service execution monitoring

40. Semantic Web Research at Tatung40 Top Level of the Service Ontology Service Resource Service Grounding ServiceProfile ServiceModel provide presents supportsdescribedBy (what it does) (how it works) (how to access it)

41. Semantic Web Research at Tatung41 Process Modeling Ontology

42. The Big Picture of SW

43. Semantic Web Research at Tatung43 Editing and Annotation Tools Protégé-2000 OntoEdit OilED Amaya

44. An Architecture of RDF Triple Data Store

45. Semantic Web Research at Tatung45 RDF Parser and Generator Using DCG in Prolog as the development tool Formal grammar in RDF M&S Spec http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/#grammar Prolog’s inference engine Formal grammar rules in DCG Prolog’s working storage User interface

46. [6.1] RDF ::= [' '] obj* [' '] [6.2] obj ::= description | container [6.3] description ::= ' ' | ' ' propertyElt* ' ' | typedNode [6.4] container ::= sequence | bag | alternative rdf(Objs) --> (['<?'], ([nm/'xml'];[nm/'XML']; [nm/'xmls'];[nm/'XMLS']), ([nm/'version','=',qs/_];[]), ([nm/'encoding','=',qs/_];[]), ['?>'],{wl('XML heading')} ;[]), (fullSTG('RDF',NS) ; halfSTG('RDF',NS), ['>'] ; [ ]), objStar(Objs), (fullETG('RDF',NS);[ ]). objStar(Out) --> obj(O), objStar(R),{Out=[O|R]} ; [],{Out=[]}. obj(Obj) --> container(Obj) ; description(_),{getAllTriples(Obj)}. getAllTriples(Obj):- findall(statement(A,B,C),statement(A,B,C),Obj). description(_) --> halfSTG('Description',NS), (idAboutAttr(IdAboutAttr);[]), (bagIdAttr(BagIdAttr);[]), propAttrStar(IdAboutAttr), (['/>'] ; ['>'], propertyEltStar(IdAboutAttr), fullETG('Description',NS)), {reificationOfStatements(IdAboutAttr,B agIdAttr)} ; typedNode.

47. [statement(about/http://www.foo.com/cool.html, Title, alt(_87882,[string/The Coolest Web Page, string/Il Pagio di Web Fuba])), statement(about/http://www.foo.com/cool.html, Identifier, bag(id/MirroredSites,[resource/http://www.foo.com.au/cool.html, resource/http://www.foo.com.it/cool.html])), statement(about/http://www.foo.com/cool.html, Creator, seq(id/CreatorsAlphabeticalBySurname,[string/Mary Andrew, string/Jacky Crystal]))] <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/metadata/dublin_core#"> Mary Andrew Jacky Crystal The Coolest Web Page Il Pagio di Web Fuba RDF input Prolog output

48. RDF Statements in RDB Tables IdNsName 1http://www.w3.org/2000/01/rdf# 2http://purl.org/metadata/dublin_core# …… IdNSPredicateName 12Creator 22Language ……… IdResourceName 1 http://www.dlib.org 2 http://www.foo.com …… IdLiteralName 1 Jacky Crystal 2English …… IdResourcePredicateLiteral 1111 2122 ………… RDF_NameSpace RDF_Predicate RDF_Literal RDF_Statement RDF_Resource

49. Semantic Web Research at Tatung49 Application Program Interfaces RDF Query language is syntactically verbose. Selecting all resources from a collection

50. Semantic Web Research at Tatung50 Application Program Interfaces get_frame - retrieves attribute values for a frame add_frame - adds or updates attribute values for a frame del_frame - deletes attribute values from a frame We propose a set of frame-based APIs for programmers to access the RDF repository.

51. Semantic Web Research at Tatung51 User Interface Natural language interface is the best choice, but is very difficult to obtain a good result. Form-based interface is easy to implement, but is too restricted. Hierarchical directory browsing is perhaps a good idea, if the domain in question is well organized. We also propose a frame-based query interface. target_concept[(attribute 1 [:value 1 ], …)] teacher(office:6th_floor)

52. Semantic Web Research at Tatung52 Related Work Jena –HP Labs in Bristol, England –Jena is an API in the Java programming language, for the creation and manipulation of RDF graphs RDFSuite –ICS, Forth, Greece –The Validating RDF Parser (VRP) –The RDF Schema Specific DataBase (RSSDB) –The RDF Query Language (RQL)

53. Semantic Web Research at Tatung53 Semantic Community Portal

54. Semantic Web Research at Tatung54 Semantic Community Portal

55. Semantic Web Research at Tatung55 Semantic Community Portal

56. Semantic Web Research at Tatung56 Conceptual Architecture of an NL QA System http://140.129.20.113:8080/daml/

57. Recap: The Big Picture of SW

58. Semantic Web Research at Tatung58 Future Work RDF schema-specific validator Frame-based RDF schema-specific query language User interface Automatic generation of community portals –Application of digital library and archives Automatic generation of FAQs Trust on the web

59. Semantic Web Research at Tatung59 Summary RDF repository –RDF parser and generator using Prolog –RDF triples storage in Prolog and RDB tables –Application program interfaces –User interfaces (inference engine) Building community portals Agent-based architecture Trust on the Web