2. © 2006 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice Use Case: Populating Business Objects W3C Workshop on RDF Access to Relational Databases Andy Seaborne (HP), Damian Steer (ILRT)

3. 3 Business Problem New business process XML objects Data in various places

4. 4 Technical Problem ? ? ? Geographic Production … ?? ?? ??... … Asset & History

5. 5 Technical Approach Single SPARQL Query Translation between domains Databases SquirrelRDF

6. 6 http://jena.sf.net/SquirrelRDF SPARQL to SQL −And LDAP and IMAP RDB Mapper −(c.f. TimBL’s Design note)Design note Simple servlet Results in SPARQL XML Results Format, JSON, … … and RDF.

7. 7 RDB Mapper Automatic Generation A map is a number of mapped classes −Not necessarily in the same database ex:map a db:Map ; db:mapsClass ex:People, ex:Department.

8. 8 RDB Mapper : Classes Tables map to classes ex:People a rdfs:Class ; db:primaryKey ex:propA ; db:database ; db:table “People". CREATE TABLE People ( id int, name varchar(30), PRIMARY KEY id )

9. 9 RDB Mapper : Properties ex:people_id a rdf:Property ; rdfs:domain ex:people ; db:col "id" ; db:colType "int". ex:people_name a rdf:Property ; rdfs:domain ex:people ; db:col "name" ; db:colType "varchar". CREATE TABLE People ( id int, name varchar(30), PRIMARY KEY id )

10. 10 SquirrelRDF Hard: SPARQL patterns with a property variable −{ ?p “foo” } Hard: Query over types −{ ?s rdf:type ?type }

11. 11 Rules SPARQL basic graph pattern −point at which data is accessed in SPARQL BGP translation −SPARQL pattern match => calculate => generate pattern −Generate pattern more than a BGP (e.g. UNION) Applied to query coming in Targeting databases left to SquirrelRDF

12. 12 Rules Used Used −Reformat a key −Property => property −Join across databases by key −Multiple places for one value Notes −In this use case, no rewriting the query results was necessary, but likely needed in other situations.

13. 13 Summary Domain mapping problem is not SQL specific −SPARQL-rewrite rules encapsulate mapping Direct database encapsulation −Scale, maintenance

14. 14

15. 15 Jena extended tools family External bridges Gloze XML XML Schema RDF OWL GRDDL XML with GRDDL annotation RDF SquirrelRDF RDF SPARQL RDBMS LDAP Joseki RDF Server DARQ distributed SPARQL query Access PortalCore Facetted browse Brownsauce RDF explorer UI Tools Eyeball Configurable RDF validator Jena Ontology API SPARQL API query & update RDF API RulesExternal None Inference Writers RDF/XML N3 Turtle N-triple Readers RDF/XML N3 Turtle N-triple Graph and query (Store SPI) Memory File backed SDB SPARQL database RDB Command line tools - merge RDF - convert format - schemagen - db load

16. 16 Example: Semantic Web Environmental Directory www.swed.org.uk

17. 17 Example: Seeker – an Education Portal for the Singapore Government