1. TU/e eindhoven university of technology PACIS'03 July 2003 1 Engineering Semantic Web Information Systems Richard Vdovjak Flavius Frasincar Geert-Jan Houben Peter Barna Databases & Hypermedia Group Department of Computer Science /dept. of mathematics and computer sciencewwwis.win.tue.nl/~hera

2. TU/e eindhoven university of technology PACIS'03 July 2003 2 Overview Motivating example: Virtual art gallery Hera framework, models and technologies Hera Back-end: Integration engine Hera front-end: Presentation generation engine Summary and future work

3. TU/e eindhoven university of technology PACIS'03 July 2003 3 Create “on-the-fly” exhibitions –painters, paintings, techniques... Many to many content delivery Triggered by the user query Exhibits (Images) are from (online) Art catalogues Descriptions are gathered from an (online) Art Encyclopedia Virtual art gallery WIS

4. TU/e eindhoven university of technology PACIS'03 July 2003 4 We need a framework that offers Semantics –Express concepts and their hierarchies –Relationships among the concepts –Query language that can exploit the above Access to several sources –Flexible source management –Flexible query mediation User/platform adaptation –(adaptability and adaptivity) Automated presentation design –Based on the user query, –Device profiles and the browsing history

5. TU/e eindhoven university of technology PACIS'03 July 2003 5 The Hera Framework: Design Steps, Models, and Processing Engines

6. TU/e eindhoven university of technology PACIS'03 July 2003 6 Overview of the System Integration Engine Presentation Engine Conceptual Model

7. TU/e eindhoven university of technology PACIS'03 July 2003 7 Conceptual Model (CM) Provides a uniform semantic view over different data sources that are integrated within a given Web application Consists of hierarchies of concepts relevant within the given domain, their properties, and relations Encoded in RDF(S)

8. TU/e eindhoven university of technology PACIS'03 July 2003 8 RDF(S), RQL RDF(S) –W3C standard for describing metadata –Directed labeled graph formalism –Formal semantics defined RQL: select X from {X:Technique}tname{Xtname} where Xtname = "Chiaroscuro"

9. TU/e eindhoven university of technology PACIS'03 July 2003 9 Conceptual Model Example

10. TU/e eindhoven university of technology PACIS'03 July 2003 10 Source Clusters Sources are Autonomous (Virtually) grouped to clusters based on the content they provide RDF(S), RQL capable

11. TU/e eindhoven university of technology PACIS'03 July 2003 11 Integration Model IM decouples the CM and Sources Articulations –actual links between the CM and the source ontologies –concept/instance uniqueness –(a part of it) serves as a query on the source side Decorations –offer a way to rank sources within the same cluster –capture explicitly designer’s knowledge about sources –the order in which the sources are consulted is flexible –open possibilities for queries with constraints e.g. “I’m interested in the answer within 1 s, otherwise forget it”

12. TU/e eindhoven university of technology PACIS'03 July 2003 12 Integration Model Ontology Application independent Path expression –Primary node (including its ID) –Sequence of nodes and edges Articulation –Target and Source path expressions Decoration –Value based ordering criterion –e.g. ResponseTime, Reliability Processing instruction –Transformers (e.g. Literal2String)

13. TU/e eindhoven university of technology PACIS'03 July 2003 13 Integration Model Instance: Articulation Example a2_1 pe_to3 pe_from3 cm:Painting ac:Painting cm:picture ac:visualized d2_1 0.9 URL2ImageTransf ac:title target source starts idByValue obtainedFrom idByValue transformedBy obtainedFrom follow ends follow http://www…ac applies srcAddress Decoration (Reliability) Source Path Expression (query for the source) Target Path Expression cm:aname endsL URL Image

14. TU/e eindhoven university of technology PACIS'03 July 2003 14 Source Management Back-end Front-end Sources User Query Presentation Integration Model IM Specialization Conceptual Model IM Instance Access Point html/smil

15. TU/e eindhoven university of technology PACIS'03 July 2003 15 Query answering Query mediation –For every variable in the query find articulations in the IM instance pool –If there more articulations for one variable sort them based on the chosen decoration(s) –Execute the “source” path expression queries at the the sources –Perform the required processing instruction/data transformations –Assemble the results

16. TU/e eindhoven university of technology PACIS'03 July 2003 16 Application Model (AM) AM serves as a presentation blue-print Describes hypermedia aspects of the presentation. Captures the navigational view over the CM Consists of (nested) slices and slice relationships –Slices - meaningful presentation units Associated to concepts from the CM Contain properties and possibly other slices (nesting) –Slice relationships: Aggregation relationships: index, tour, indexed guided tour… Reference relationships: link with an anchor specified. Encoded in RDF(S).

17. TU/e eindhoven university of technology PACIS'03 July 2003 17 Application Model Example

18. TU/e eindhoven university of technology PACIS'03 July 2003 18 Adaptation/User Model Captures two kinds of adaptation –Adaptability takes into account the situation in which the user will use the presentation (e.g. the browsing platform). –Adaptivity means that the presentation changes itself according to the “state of the user’s mind” while being browsed. Consists of –Device/User Profile captures “static” visual and platform preferences encoded in CC/PP. –User Session represents the dynamic user’s state, e.g. did the user visit (learn) this slice (concept). –Application and Update Rules describe the behavior of the presentation (e.g. conditional slices in AM) and keep the User Session up-to-date (AHAM rules).

19. TU/e eindhoven university of technology PACIS'03 July 2003 19 Adaptation Model Example

20. TU/e eindhoven university of technology PACIS'03 July 2003 20 Adaptation Model Syntax Adaptability Condition Adaptivity Condition <rdfs:Class rdf:ID=“Slice.painter.main” slice:condition=“um:Technique <rdfs:Class rdf:ID=“Slice.painting.picture” slice:condition=“prf:ImageCapable=Yes”>

21. TU/e eindhoven university of technology PACIS'03 July 2003 21 Profile Example Device/User Profile (CC/PP encoding) Screen size: 100x80, preferred language: English English … No 100x80 …

22. TU/e eindhoven university of technology PACIS'03 July 2003 22 XSL Rendering XSLT code generation Different code generators: –HTML for PC Web browsers –SMIL code for multimedia presentations –WML code for WAP phone browsers XSL HTML WML

23. TU/e eindhoven university of technology PACIS'03 July 2003 23 Resulting Hypermedia Presentations HTML WML SMIL

24. TU/e eindhoven university of technology PACIS'03 July 2003 24 EROS: exploring the CM Explorer for RDFS- based OntologieS multiple views over the same model support for RQL queries construction

25. TU/e eindhoven university of technology PACIS'03 July 2003 25 Summary CM in RDF, RDFS RQL IM Articulations IM Decorations AM in RDF, RDFS UM, U/P Profile (CC/PP) Hera: Semantics –Express concepts and their hierarchies –Relationships among the concepts –Query language that can exploit the above Access to several sources –Flexible source management –Flexible query mediation User/platform adaptation –(adaptability and adaptivity) Automated presentation design –Based on the user query, –Device profiles and the browsing history

26. TU/e eindhoven university of technology PACIS'03 July 2003 26 Present & Future Work Applying our approach in different domains –Virtual museum –Photo Portal –Medical science (drug/disease ontologies) Optimization issues Authoring tools for the underlying models –Initial correlation for Schema Integration