The NERC DataGrid Vocabulary Server: an operational system with distributed ontology potential

1. GO-ESSP 2008, Seattle, September 2008 The NERC DataGrid Vocabulary Server: an operational system with distributed ontology potential Roy Lowry British Oceanographic Data Centre

2. Presentation Summary • What we’ve got • How to use it • What’s wrong with it? • What we’re doing about it • What’s in it for CF?

3. What We’ve Got • Server Contents (2008-08-21) • 112 public lists • 122603 concepts • 78123 mappings (RDF triples) • Server Usage 2008 (to 2008-08-21) • 2233803 total hits (2000000 of these attributable to robots) • 37462 vocabulary catalogue hits • 50458 vocabulary list downloads • 2085 vocabulary mapping queries • In summary a heavily populated, heavily used system

4. How to Use It • There are four ways to access vocabulary content • Term and list URLs • HTTP-POX web service calls • SOAP web service calls • Interface clients

5. How to Use It • Term and list URLs • Any list may be accessed using a URL of the form http://vocab.ndg.nerc.ac.uk/list/list_id/list_version • Delivers the list, without mappings, as a SKOS XML document • Any term my be accessed using a URL of the form http://vocab.ndg.nerc.ac.uk/term/list_id/list_version/term_id • Delivers the term, including all mappings, as a SKOS XML document

6. How to Use It <?xml version="1.0" ?> - <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:skos="http://www.w3.org/2004/02/skos/core#" xmlns:dc="http://purl.org/dc/elements/1.1/"> -<skos:Concept rdf:about="http://vocab.ndg.nerc.ac.uk/term/P021/25/PHYC"> <skos:externalID>SDN:P021:25:PHYC</skos:externalID> <skos:prefLabel>Phycobolin pigment concentrations in the water column</skos:prefLabel> <skos:altLabel>WC_PhycobolPig</skos:altLabel> <skos:definition>Concentration of phycobolin group pigments such as phycocyanin and phycoerythrin in the water column</skos:definition> <dc:date>2008-03-11T11:56:27.531+0000</dc:date> <skos:minorMatch rdf:resource="http://vocab.ndg.nerc.ac.uk/term/P041/4/G905" /> <skos:broadMatch rdf:resource="http://vocab.ndg.nerc.ac.uk/term/P031/8/B035" /> <skos:broadMatch rdf:resource="http://vocab.ndg.nerc.ac.uk/term/P041/4/G378" /> <skos:broadMatch rdf:resource="http://vocab.ndg.nerc.ac.uk/term/P051/0/002" /> <skos:broadMatch rdf:resource="http://vocab.ndg.nerc.ac.uk/term/P051/0/014" /> <skos:narrowMatch rdf:resource="http://vocab.ndg.nerc.ac.uk/term/P011/79/PHYCSPP4" /> </skos:Concept> </rdf:RDF>

7. How to Use It • HTTP-POX service calls • Any API method may be invoked using an HTTP get call • Lists and terms specified in the get call parameters as URLs • Delivers an appropriate XML document (BODC-designed schema) • Documentation at http://www.bodc.ac.uk/products/web_services/vocab/methods.html • SOAP web service calls • WSDL may be found at http://vocab.ndg.nerc.ac.uk/ • Same output and documentation as HTTP-POX

8. How to Use It • Interface clients • Maris client set up for SeaDataNet at http://seadatanet.maris2.nl/v_bodc_vocab/welcome.aspx • BODC clients at http://vocab.ndg.nerc.ac.uk/ cover more vocabularies if interests extend beyond SeaDataNet

9. How to Use It • Typical Maris client output

10. How to Use It • In SeaDataNet vocabulary terms are included in data and metadata as URNs • These have the form: • SDN:list_id:list_version:term_id, e.g. • SDN:P021:23:TEMP • SDN:P021::TEMP (for current version) • URNs resolve to URLs by simple string substitution (service to do this planned) • URLs may be used to obtain the term identifiers, labels and mappings in an XML document

11. What’s Wrong With It? • Historic version serving not implemented • Current version served whatever version is requested • Predicates (SKOS mappings) semantically limited • More suited to a thesaurus rather than an ontology • Richer set in the triple store, but cannot be served without WSDL changes

12. What’s Wrong With It? • Vocabularies not labelled with content governance authority • Mappings restricted to concepts within the server • If a vocabulary is to be included in a mapping then it must be loaded in the server • Not exactly Semantic Web!

13. What We’re Doing About It • Historic version serving not implemented • Necessary SQL now written so functionality will be incorporated into the next release • Predicates (SKOS mappings) semantically limited • Collaboration with Sean Bechhofer (Manchester Computer Science) to design better SKOS documents for server payload

14. What We’re Doing About It • Vocabularies not labelled with content governance authority • On the list of things to do for version 1.2 • Mappings restricted to concepts within the server • Developing interoperable server in collaboration with ICES • Triple store structural redesign under consideration

15. What We’re Doing About It • In practice • V1.2 planned for the end of the year • Historic version serving • Vocabularies labelled with content governance • V2.0 date not yet fixed • Linkage to external resources • Improved SKOS document payload

16. What’s in it for CF? • Currently serve Standard Names and Cell Methods • Synchronised with CF site (Alison provides update material) • Mappings maintained to SeaDataNet (BODC) and GCMD vocabularies • Support for representation of Standard Names as URLs that may be mapped and used as URNs

17. That’s All Folks Thank you for your Attention Any Questions?