Registry of MEG-related schemas MEG BECTa, Coventry, 17 July 2001 Pete Johnston UKOLN, University of Bath Bath, BA2 7AY UKOLN is supported by: Email [email protected]

Registry of MEG-related schemas

MEG

BECTa, Coventry, 17 July 2001

Pete Johnston

UKOLN, University of Bath

Bath, BA2 7AY

UKOLN is supported by:

[email protected]://www.ukoln.ac.uk/

MEG,BECTa,Coventry, 17 July 2001

2

Registry of MEG-related metadata schemas

• How metadata schemas are used• Types of schemas• Schema registries and their uses• Some issues


3

How metadata schemas are used

• Implementers use standard schemas in pragmatic way

• Standards creators– integrity of model, consensus, commonality,

interoperability

• Implementers– service delivery, specificity, localisation

• Standard solutions published• Implementer adaptations/extensions not

widely available


4

Types of schemas

• Namespace schema– a type of schema– only declare names and definitions

• Application profile– a type of schema– describes use of terms by application


5

Application profiles

• (Re)use terms defined in namespace schemas

– may combine terms from multiple namespace schemas

– may adapt/refine semantic definitions– may specify permitted schemes for values

of elements– may mandate element usage, occurrence


6

Machine-readable schemas

• Namespace schema– RDF Schema– RDF/XML representation

• Application profile– (presently) no standard convention– SCHEMAS project developing RDF-based

convention– XML schema approach possible?– explicit cross reference from description of

element use in AP to declaration in NS


7

Schemas registries

• To provide a publication context for namespace schemas & application profiles

– standard definitions of terms– by whom?

– usage/adaptations of terms– by whom?

– annotations, commentaries, evaluations– by whom?


8

Schemas registries (2)

• To provide a dictionary of terms– names, definitions, usage– relationships between terms

• Prescribe (standards) and describe (usage)

• Support evolution of schemas– top-down (standards authorities)– bottom-up (real world usage)

• Disclosure, discovery, effective reuse, harmonisation


9

Schemas registries (3)

• Might “contain”– schemas

– namespace schemas– application profiles

– information about schemas (annotations)– guidelines– evaluations, commentaries etc.

– schemes– controlled vocabularies, thesauri

– mappings between schemas– pointers

– to users, implementers, projects, tools


10

Recent entries in MEG registry

• MILO– namespace schema– application profile

• QCA/National Curriculum– namespace schema– application profile

• Virtual Teacher Centre– namespace schema– application profile


11

Users of a schemas registry

• Human– publishers of standards– implementers of AP’s– developers seeking schemas– developers mapping between schemas– researchers studying schemas

• Functions– Search for schemas, elements– View, navigate schemas– View annotations etc

N.B. Desire registry human-readable only


12

Users of a schemas registry (2)

• Software tools e.g.– metadata instance editor– metadata instance validator– metadata transformation/conversion– application profile development tool– … etc!

• Functions– Retrieve element definition– Retrieve usage description (including vocabularies

etc)– Retrieve definition of semantically equivalent

term….


13

Thick registry : database

ThickRegistry

Namespaceschema App

profile

Sampledata

Mapping

Usageguide

Software tools Users


14

Thin registry : portal

Thin Registry

Namespaceschema App

profile

Sampledata

Mapping

Usageguide

Software tools Users


15

Technology of registries

• RDF and RDF(S) provide foundations• EOR (Extensible Open RDF) toolkit

– Eric Miller (formerly of OCLC)– open source– extensible set of Java classes– support for generic RDF

• Registry as application built on EOR– harvests RDF schemas– parses, stores, indexes– provides interface for query, navigation


16

Some issues

• DESIRE registry– human readable only

• SCHEMAS project– human and machine readable

• Concepts still evolving• Scope of registries?

– finding (the right) registry?

• Communicating with a registry?– functions required? minimal functionality?– interfaces for registries?– describing registries?


17

Acknowledgements / further reading

Rachel Heery & Manjula Patel, Application Profiles http://www.ariadne.ac.uk/issue25/app-profiles/

Tom Baker, A Grammar of Dublin Corehttp://www.dlib.org/dlib/october00/baker/10baker.html

Stuart Weibel, The DCMI: Status & Plans (2001)http://www.cimi.org/public_docs/CIMI-2001-06.ppt

Jane Hunter, Combining RDF and XML Schemas….http://archive.dstc.edu.au/RDU/staff/jane-hunter/www10/paper.html

SCHEMAS project: http://www.schemas-forum.org/

DCMI Registry:http://dublincore.org/groups/registry/

Documents

Registry of MEG-related schemas MEG BECTa, Coventry, 17 July 2001 Pete Johnston UKOLN, University of Bath Bath, BA2 7AY UKOLN is supported by: Email [email protected]