1. The MEG Metadata Schemas Registry: Architecture & Data Model MEG Registry Workshop, Bath, 21 January 2003 Pete Johnston UKOLN, University of Bath Bath, BA2 7AY UKOLN is supported by: p.johnston@ukoln.ac.uk http://www.ukoln.ac.uk/

2. MEG registry workshop,Bath, 21 January 2003 2 MEG Metadata Schemas Registry Architecture & Data Model Architecture –“What does it do? How does it work?” (briefly!) –Outline of functional components –Interfaces between components Data model –“What are we talking about?” –Resources described –Relationships between resources –Attributes/properties of those resources

3. MEG registry workshop,Bath, 21 January 2003 3 The registry Developed by (client) Damian Steer, (server) Dave Beckett (ILRT, University of Bristol) Accepts machine-readable descriptions of (specific types of) resources –types of resource to be described –see data model (Element Sets, Elements etc) –descriptions stored in Schemas (RDF/XML) –publication API (HTTP POST) Indexes those descriptions Provides browse/search interfaces to those indexes for –human readers (HTML) –software tools –query API (HTTP GET)

4. MEG SCART (Client) Vocabulary managers Schemas (RDF/XML) MEG Registry (Server) Registry Publish API (HTTP POST) Information seekers Registry HTML interface Applications (including other Registries) Registry Query API (HTTP GET) today

5. MEG SCART (Client) Vocabulary managers Schemas (RDF/XML) MEG Registry (Server) Registry Publish API (HTTP POST) Information seekers Registry HTML interface Applications (including other Registries) Registry Query API (HTTP GET) Other applications Vocabulary managers

6. MEG registry workshop,Bath, 21 January 2003 6 The registry data model A simplification of complexity A basis for comparison Classes of resource described –Element Sets –Elements –Encoding Schemes –Values in controlled vocabularies –Application Profiles –Element Usages Descriptions stored in Schemas –Schemas themselves not described

7. Agency Element Set App Profile Encoding Scheme Element Usage Value 1m 1 m 1 m mm 1m m m 1 m 1 m 1 m m 1

8. MEG registry workshop,Bath, 21 January 2003 8 Agency Relationships –Element Set --- is-Managed-By (m-1)  Agency –Encoding Scheme --- is-Managed-By (m-1)  Agency –Application Profile --- is-Managed-By (m-1)  Agency An organisation or individual responsible for managing one or more Element Sets, Application Profiles or Encoding Schemes

9. MEG registry workshop,Bath, 21 January 2003 9 Agency properties Identifier (URI) NameThe name or title of the Agency Home Page URLA source of further info about the Agency

10. MEG registry workshop,Bath, 21 January 2003 10 Element Set Relationships –Element Set --- is-Managed-By (m-1)  Agency –Element --- is-Element-Of (m-1)  Element Set A set of metadata Elements that is managed as a coherent unit by an Agency. The Elements of an Element Set are “functionally” related, by virtue of having been defined for the purpose of usefully describing the characteristics of a resource

11. MEG registry workshop,Bath, 21 January 2003 11 Element Set properties Identifier (URI) TitleThe name or title of the Element Set VersionThe version of the Element Set Date createdDate this version created StatusDraft/recommendation etc DescriptionIncluding any notes of scope/purpose.

12. MEG registry workshop,Bath, 21 January 2003 12 Element Set properties Classification XML NamespaceDo not use SpecificationProse description of/guidelines for use of Element Set

13. MEG registry workshop,Bath, 21 January 2003 13 Element Relationships –Element --- is-Element-Of (m-1)  Element Set –Element --- associated-Encoding-Scheme (m- m)  Encoding Scheme –Element --- refines (m-1)  Element –Element Usage – uses (m-1)  Element A formally defined term that is used to describe a characteristic or attribute of a resource

14. MEG registry workshop,Bath, 21 January 2003 14 Element properties Identifier (URI) NameA human-readable version of the property name DefinitionA statement that clearly represents the concept and essential nature of the Element CommentA remark concerning the application/use of the data element

15. MEG registry workshop,Bath, 21 January 2003 15 Element properties Data typeIndicates the type of data that can be represented in the value of the data element ObligationIndicates whether the Element is always or sometimes required to be present Maximum occurrenceIndicates any limit to the repeatability of the Element

16. MEG registry workshop,Bath, 21 January 2003 16 Encoding Scheme Relationships –Encoding Scheme --- is-Managed-By Agency (m-1)  Agency –Element --- associated-Encoding-Scheme (m- m)  Encoding Scheme –Element Usage --- associated-Encoding- Scheme (m-m)  Encoding Scheme –Value – type (m-1)  Encoding Scheme A set of contextual information or parsing rules that aids in the interpretation of the value of a metadata Element. Encoding Schemes include –controlled vocabularies, which enumerate a list of values, and; –formal notations or parsing rules, which define precisely how a lexical representation of a value is to be interpreted

17. MEG registry workshop,Bath, 21 January 2003 17 Encoding Scheme properties Identifier (URI) NameThe name or title of the Encoding Scheme VersionThe version of the Encoding Scheme Date createdDate this version created StatusDraft/recommendation etc DescriptionIncluding any notes of scope/purpose.

18. MEG registry workshop,Bath, 21 January 2003 18 Encoding Scheme properties Classification SpecificationProse description of/guidelines for use of Encoding Scheme

19. MEG registry workshop,Bath, 21 January 2003 19 Controlled Vocabulary Value Relationships –Value – type (m-1)  Encoding Scheme An individual value or term in a controlled vocabulary

20. MEG registry workshop,Bath, 21 January 2003 20 Controlled Vocabulary Value properties Identifier (URI) Value LabelHuman-readable form of value DescriptionExplanation or definition of value

21. MEG registry workshop,Bath, 21 January 2003 21 Application Profile A set of Element Usages that is managed as a coherent unit by an Agency. An Application Profile is optimised for the resource description requirements of a particular application or context. Like the Elements of an Element Set, the Element Usages within an Application Profile are “functionally” related, by virtue of having been defined for the purpose of usefully describing a resource. Within an Application Profile, the Element Usages may reference Elements from multiple Element Sets

22. MEG registry workshop,Bath, 21 January 2003 22 Application Profile Relationships –Application Profile --- is-Managed-By Agency (m-1)  Agency –Element Usage --- is-Usage-In (m-1)  Application Profile

23. MEG registry workshop,Bath, 21 January 2003 23 Application Profile properties Identifier (URI) TitleThe name or title of the Application Profile VersionThe version of the Application Profile. Date createdDate this version created StatusDraft/recommendation etc DescriptionIncluding any notes of scope/purpose.

24. MEG registry workshop,Bath, 21 January 2003 24 Application Profile properties Classification Associated XML Schema SpecificationProse description of/guidelines for use of Application Profile

25. MEG registry workshop,Bath, 21 January 2003 25 Element Usage Relationships –Element Usage --- is-Usage-In (m-1)  Application Profile –Element Usage --- uses (m-1)  Element –Element Usage --- associated-Encoding- Scheme (m-m)  Encoding Scheme A deployment of a (previously defined) metadata Element in the context of a particular domain or application. The used Element may be tailored for the context by: –a narrowing of its semantic definition; –association with specified datatypes or Encoding Schemes; –specification of obligation/occurrence constraints

26. MEG registry workshop,Bath, 21 January 2003 26 Element Usage properties Identifier (URI) NameA human-readable version of the Element name. DefinitionA statement that clearly represents the concept and essential nature of the Element. CommentA remark concerning the application/use of the Element.

27. MEG registry workshop,Bath, 21 January 2003 27 Element Usage properties Data typeIndicates the type of data that can be represented in the value of the Element ObligationIndicates whether the Element is always or sometimes required to be present Maximum occurrenceIndicates any limit to the repeatability of the Element

28. MEG registry workshop,Bath, 21 January 2003 28 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.

29. MEG registry workshop,Bath, 21 January 2003 29 In practice…. Easier to understand by using the tools and seeing examples…..

30. MEG registry workshop,Bath, 21 January 2003 30 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/