The MEG Metadata Schemas Registry Schemas and Ontologies: building a Semantic Infrastructure for GRIDs and digital libraries Edinburgh, 16 May 2003 Pete Johnston UKOLN, University of Bath Bath, BA2 7AY p.johnston@ukoln.ac.uk http://www.ukoln.ac.uk/ UKOLN is supported by:
MEG Metadata Schemas Registry Background : MEG Architecture Data model 2 Schemas & ontologies, UKOLN/NeSC Workshop, Edinburgh, 16 May 2003
The registry Metadata for Education Group (MEG) facilitated by Interoperability Focus forum for discussing provision of educational resources at all levels across UK encourage consistency of approaches to description use of DESIRE registry MEG registry project 2002 Funded by JISC/BECTa (Essentially) re-engineering of DESIRE registry as RDF application Shaped by work in SCHEMAS project Some refinement of data model Uses RDFS, but not (currently) OWL 3 Schemas & ontologies, UKOLN/NeSC Workshop, Edinburgh, 16 May 2003
The registry Developed by Client (Damian Steer): Java, Jena (HP labs) Server (Dave Beckett ILRT, University of Bristol): Perl, Redland Reads machine-readable descriptions of metadata vocabularies descriptions stored in Schemas (RDF/XML) publication API (HTTP POST) Indexes those descriptions Provides browse/search interfaces for human readers (HTML) software tools query API (HTTP GET) 4 Schemas & ontologies, UKOLN/NeSC Workshop, Edinburgh, 16 May 2003
Vocabulary managers Other Applications (including other Registries) Information seekers MEG Client RDF/XML (Schemas) Web browser RDF/XML RDF/XML Upload API (HTTP POST) Query API (HTTP GET) HTML browse interface RDF/XML (Schemas) MEG Registry (Server) Database
The registry data model A simplification of complexity A basis for comparison Based on Dublin Core "Grammatical Principles" Elements Element Refinements Encoding Schemes "Application Profile" May "use" elements from multiple element sets May specify obligation/cardinality May specify encoding schemes May narrow "standard" element semantics 6 Schemas & ontologies, UKOLN/NeSC Workshop, Edinburgh, 16 May 2003
The registry data model Classes of resource described Element Sets Elements Encoding Schemes Values in Controlled Vocabulary Encoding Schemes Application Profiles Element Usages Agencies Descriptions stored in Schemas Schemas themselves not (currently) described Potentially, many-to-many relation between Schema and (any of above!) 7 Schemas & ontologies, UKOLN/NeSC Workshop, Edinburgh, 16 May 2003
Element Set m 1 Agency 1 1 1 m m m Element m m Encoding Scheme 1 m Value 1 1 m m m m Element Usage m 1 App Profile
Key relations for Elements An Element is-element-of exactly one Element Set An Element Usage is-usage-in exactly one Application Profile An Element Usage uses exactly one Element The several Element Usages in one Application Profile may use Elements from different Element Sets. 9 Schemas & ontologies, UKOLN/NeSC Workshop, Edinburgh, 16 May 2003
1. Registry browse menu
2. Browse Agencies
3. Display Agency
4. Display Element Set
5. Display Element
6. Display Element Usage
7. Display Application Profile
8. Display Element Usage
1. Launch client Create Agency description
2. Create Agency description Add Agency description to Schema
3. Create Application Profile description Select Application Profile browser Create Application Profile description
4. Create Application Profile description Add AP details Add AP description to Schema
5. Create Element Usage description Drag Element To Profile Search registry for title Elements
6. Create Element Usage description Add Element Usage details Add Element Usage description to Schema
7. Create Encoding Scheme description Switch from Simple to Advanced mode Select Encoding Scheme browser Create Encoding Scheme description
8. Create Encoding Scheme description Add Encoding Scheme details Add Encoding Scheme description to Schema
18. Associate Scheme with Usage Drag Scheme to Usage
10. Save Schema as RDF/XML File -- Save As
11. Submit Schema to Server Click to submit Confirm Finish
Some issues Is the registry data model generally useful? Or too simple? Too DC-oriented? Many "real world" metadata applications don't (yet?) adopt RDF model To what extent can registry support XML applications? 29 Schemas & ontologies, UKOLN/NeSC Workshop, Edinburgh, 16 May 2003
Acknowledgements UKOLN is funded by Resource: the Council for Museums, Archives and Libraries, the Joint Information Systems Committee (JISC) of the UK higher and further education funding councils, as well as by project funding from the JISC and the European Union. UKOLN also receives support from the University of Bath where it is based. http://www.ukoln.ac.uk/ 30 Schemas & ontologies, UKOLN/NeSC Workshop, Edinburgh, 16 May 2003