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WSMO – UDDI Semantics Review

WSMO – UDDI Semantics Review. Taxonomies and Value Sets Discussion Paper Max Voskob (mvoskob@msi.net.nz) – February 2004 UDDI Spec TC V4 Requirements Taxonomy Support for Semantics Max Voskob (mvoskob@msi.net.nz) – February 2004 Presenter: Matt Moran, NUIG-DERI, 16 Feb 2004.

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WSMO – UDDI Semantics Review

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  1. WSMO – UDDI Semantics Review Taxonomies and Value SetsDiscussion Paper Max Voskob (mvoskob@msi.net.nz) – February 2004 UDDI Spec TC V4 RequirementsTaxonomy Support for Semantics Max Voskob (mvoskob@msi.net.nz) – February 2004 Presenter: Matt Moran, NUIG-DERI, 16 Feb 2004

  2. WSMO – UDDI Semantics Review Taxonomies and Value Sets - Discussion • Overview • Enabling UDDI to use metadata with external knowledge will allow UDDI registries to align with Semantic Web technologies • Four Scenarios • Ontology points to UDDI • UDDI points to Ontology • RDF-bag points to Ontology • UDDI Value set points to Ontology

  3. WSMO – UDDI Semantics Review Scenario 1: Ontology points to UDDI Issues- Tight coupling of UDDI to ontology- UDDI must understand ontology or use an external provider for validationBenefits- Reasoning engine can work directly with ontology without UDDI Scenario 2: UDDI points to Ontology Description- Category bag key identifies the ontology- Name points to the unique concept ID in the ontology- Value may provide the key of a related UDDI entityIssues- Validation as in scenario 1 - Hard to describe many-to-many or even one-to-many relationships

  4. WSMO – UDDI Semantics Review Scenario 3: RDF-Bag points to Ontology Description- UDDI has additional RDF bag next to category and identifier bags- RDF statements can be free or follow an RDFS schemaIssues- UDDI must understand RDF- RDF query language may be required- Validation as in scenarios 1 and 2Benefits- Rich metadata with every UDDI entity- Any standard can be used for ontology as long as consistent with Sem Web Scenario 4: Value Set points to Ontology Description- Ontology owner provides a value set corresponding to ont.- UDDI uses value set for syntax and value validation- Key-name-value triples link to concepts in the ontologyIssues- Information loss in transformation to value set - Maintenance of value set over time very awkward

  5. WSMO – UDDI Semantics Review Part 2: Taxonomy Support for Semantics • Overview • Current UDDI categorisbnation is limited to value sets and direct value matching • This document proposes adding an RDF bag to UDDI to enable the use of ontologies for search • Three Scenarios • Find entity by browsing the Ontology • Find entity using semantic engine (ext. or int.) • A combination of the first two scenarios

  6. WSMO – UDDI Semantics Review Scenario 1: Find entity – Browse Ontology- Search ontology to find UDDI categories- Find entities in UDDI based on these categories- Ask UDDI server for related categories. It does this by invoking an internal or external inference engine Scenario 2: Find entity – Search (Internal Semantic Engine)

  7. WSMO – UDDI Semantics Review Scenario 2b: Find entity – Search (External Semantic Engine)

  8. WSMO – UDDI Semantics Review Scenario 3: Find entity – combined browsing and searching

  9. WSMO – UDDI Semantics Review Requirements • Ontology format – any RDF compatible • UDDI Client should be able to: • Locate ontologies with a particular UDDI server • Browse ontologies • Use ontologies to specify search criteria • RDF Bag • Checked or unchecked • If checked must be able to validate syntactically and semantically • Can be attached to any UDDI entity with category/id bags

  10. WSMO – UDDI Semantics Review UDDI Changes – Use Cases • Entity owner prepares an RDF Bag • Ontology owner creates and maintains ontology • UDDI syntactically and semantically validates RDF Bag • User or agent uses ontology to search UDDI using RDF Bag UDDI Changes – New Structures • New bag for metadata described by RDFS or XSD

  11. WSMO – UDDI Semantics Review Issues • Inference Engines – Who will provide them? • Syntactical validation requires understanding of RDFS or XSD • Semantic validation requires a standardised API between inference engine and the UDDI client • Semantic validation can be prohibitively expensive • RDF Querying – no winner language • RDF-Bag use RDF or XML? • RDFS or XSD for syntactic validation or both? • What ontology language – OWL preferred

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