1. department of computer science and engineering Two Layer Mapping from Database to RDF Martin Švihla svihlm1@fel.cvut.cz Research Group Webing Department of Computer Science FEE CTU Prague KEG 9.12.2004

2. Two Layer Mapping from Database to RDF (2) department of computer science and engineering Content ● a brief introduction to Semantic web ● problem overview – generating of metadata ● mapping from database to RDF ● METAmorphoses – two layer mapping model ● use case ● conclusion ● future work

3. KEG 9.12.2004 Two Layer Mapping from Database to RDF (3) department of computer science and engineering What is Semantic web? Semantic web is an extension of the current web, in which data are described so that computers can understand meaning of an information. Semantic web is not separate web but an extension of the current one. Semantic web is not separate web but an extension of the current one. This concept should enable better cooperation between computers and people. This concept should enable better cooperation between computers and people.

4. KEG 9.12.2004 Two Layer Mapping from Database to RDF (4) department of computer science and engineering How to create RDF metadata? ● manual anotation of existing HTML presentations ● by author when page is created ● existing web resources by community ● dynamical generation of metadata ● from wrapped HTML pages ● from database

5. KEG 9.12.2004 Two Layer Mapping from Database to RDF (5) department of computer science and engineering Dynamical generation of metadata from DB ● mapping from database structure to RDF according to given ontology

6. KEG 9.12.2004 Two Layer Mapping from Database to RDF (6) department of computer science and engineering Motivation for our work Main problems: ● flexibility ● usability Solution – two layers: ● mapping layer (complexity, flexibility) ● template layer (simple programmer interface)

7. KEG 9.12.2004 Two Layer Mapping from Database to RDF (7) department of computer science and engineering Two layer mapping mapping layer SQL query RDF tag label template name ontology DB mapping fragments: classes properties variables conditions

8. KEG 9.12.2004 Two Layer Mapping from Database to RDF (8) department of computer science and engineering Two layer mapping template layer mapping layer SQL query RDF tag label template name ontology DB RDF mapping fragments: classes properties variables conditions using fragments to create RDF document

9. KEG 9.12.2004 Two Layer Mapping from Database to RDF (9) department of computer science and engineering Mapping layer sample </mmm:Property></mmm:Class> SQL query RDF tag label template name

10. KEG 9.12.2004 Two Layer Mapping from Database to RDF (10) department of computer science and engineering Template layer sample $username$ $username$ </mmt:Condition></mmt:putInstance></mmt:putProperty></mmt:putInstance>

11. KEG 9.12.2004 Two Layer Mapping from Database to RDF (11) department of computer science and engineering Layers „Mapping layer“ ● mapping from SQL to ontology ● creates tags for template layer ● grants validity of RDF „Template layer“ ● defines final form of RDF ● uses tags from mapping layer ● used by programmer

12. KEG 9.12.2004 Two Layer Mapping from Database to RDF (12) department of computer science and engineering Layers „Mapping layer“ ● mapping from SQL to ontology ● creates tags for template layer ● grants validity of RDF „Template layer“ ● defines final form of RDF ● uses tags from mapping layer ● used by programmer

13. KEG 9.12.2004 Two Layer Mapping from Database to RDF (13) department of computer science and engineering Test use case ● we implemented METAmorphoses processor ● we used the processor to generate RDF metadata as an extension to HTML presentation of our department Dynamical, fast, up-to-date and cheap semantic web presentation contains information about entities of the department.

14. KEG 9.12.2004 Two Layer Mapping from Database to RDF (14) department of computer science and engineering Conclusion (1) Pros: ● usability (programmer doesn't have to know ontology) ● reliability (valid RDF) ● flexibility (any ontology can be used) ● speed (no RDF or OWL API is used) Cons: ● it is not possible to query database dynamically

15. KEG 9.12.2004 Two Layer Mapping from Database to RDF (15) department of computer science and engineering Conclusion (2) Areas of possible use: ● dynamical web sites with a clear structure (a list, a tree) ● e-shop catalogs ● school web presentations ●...

16. KEG 9.12.2004 Two Layer Mapping from Database to RDF (16) department of computer science and engineering Future work ● mapping editor (for mapping layer) ● more simple programmer interface (for template layer) ● jsp custom tag lib ● collaboration with some URI system ● real and useful example

17. KEG 9.12.2004 Two Layer Mapping from Database to RDF (17) department of computer science and engineering ? comments and questions......thank you svihlm1@fel.cvut.cz