Primer Taller en Grid Computing Universidad del Valle, Cali, Colombia January 2007 WS-DAIOnt-RDF(S): RDF(S) Ontology Access Oscar Corcho 1, Miguel Esteban 2 1 University of Manchester, 2 Universidad Politécnica de Madrid

2Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Outline  Introduction and Motivation  Interface organization  Interface specification  Summary

3Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Motivation  Current Semantic Grid Applications access ontologies using Semantic Web technologies  No Grid compliant ontology access mechanisms for RDF(S) and OWL ontologies that exploit resource sharing capabilities  No specialized ontology registries  No Grid compliant instance access mechanisms in RDF

4Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 The RDF(S) Access Vision  What is all about?  Providing an access mechanism to RDF(S) data sources  Two different means for interacting:  Query access: using SPARQL  Ontology access: using ontological primitives based on the RDF(S) model  Alternative, but not exclusive!  Use each one according to your needs…

5Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 What is WS-DAIOnt?  Specification of Grid Compliant Ontology Services, which  Defines a framework for creating ontology access services in a Grid environment  Is fully compliant with S-OGSA (consequently with OGSA)  Is based on up-to-date Grid standards (GGF) WS-DAI  Is based on Web Service standards (OASIS, W3C) WS-RF, WS-Addressing...  Formal name  Web Services Data Access and Integration – The Ontology Realization

6Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Data access in OGSA  OGSA provides data access and integration services (DAIS) that are well suited for building the ontology access protocol  The DAIS are organized hierarchically with the WS-DAI specificiation on top and specific realizations below:  WS-DAI defines:  A set of patterns for defining messages, operations and interfaces  A set of basic properties for describing the services and associated resources capabilities  The realizations provide specialized access to well-defined resources

7Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 How does this fit with the WS-DAI approach  Why WS-DAI approach?  After all, we are talking about data access, where else could have it fitted in?  How does this fit into the WS-DAI approach?  New realizations for providing specilized data access

8Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 What is RDF(S)?  RDF(S) = RDF + RDFS  RDF: Resource Description Framework A framework for representing information in the Web  Framework = Built-in vocabulary (Abstract Syntax) + Entailment Rules (Formal Semantics)  RDFS: Resource Description Framework Schema A RDF vocabulary for building RDF vocabularies  W3C Standards since Feb 2004

9Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Outline  Introduction and Motivation  Interface organization  Interface specification  Summary

10Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface organization  Two layers:  Bulk access  Specialized access  Interface types:  Native interfaces: mimic classes of the RDF(S) data model  Utility interfaces: provide additional functionalities that enhance usability  Message definition:  Direct data access: Retrieval of directly associated information Creation of new data (including attachments) Deletion of existing data (including detachments)  Indirect data access Delegation of access to services that provide specialized access to a subset of associated information

11Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 WS-DAIOnt-RDF(S) Implementation Architecture  Web Services Data Access and Integration – The Ontology Realization  First implementation focused on RDF(S): WS- DAIOnt-RDF(S)  Sesame and Jena Future: Oracle RDF-store  Query languages: SPARQL, SeRQL, RDQL, RQL  Two-tier architecture  Web Service tier Upper service layer Intermediate service layer Lower service layer  RDF(S) access tier RDFSConnector Storage layer

12Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Implementation and Specification

13Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Where we are moving to…

14Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface organization (II) Overall organization

15Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Outline  Introduction and Motivation  Interface organization  Interface specification  Summary

16Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface specification (I) Repository

17Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface specification (II) RepositoryFactory

18Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface specification (III) Resource

19Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface specification (IV) Class

20Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface specification (V) Property

21Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface specification (VI) Statement

22Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface specification (VII) List

23Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface specification (VIII) ListFactory

24Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface specification (IX) Container

25Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface specification (X) ContainerFactory

26Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface specification (XI) ContainerIterator

27Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Interface specification (XII) Alt

28Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Outline  Introduction and Motivation  Interface organization  Interface specification  Summary

29Primer Taller en Grid Computing. Universidad del Valle, Cali, Colombia. January 2007 Summary  Ontology-based access operations  Provided interfaces that,  Mimic main classes of the data model, or  Abstract useful functionalities that enhance usability  Followed object-oriented principles  Some figures:  12 interfaces provided  125 operations available  18 faults defined