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An introduction to metadata Metadata : from soup to nuts, NOF-digitise programme seminar, London, 5 February 2002

An introduction to metadata Metadata : from soup to nuts, NOF-digitise programme seminar, London, 5 February 2002. Email p.johnston@ukoln.ac.uk URL http://www.ukoln.ac.uk/. Pete Johnston UKOLN, University of Bath Bath, BA2 7AY. UKOLN is supported by:. An introduction to metadata.

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An introduction to metadata Metadata : from soup to nuts, NOF-digitise programme seminar, London, 5 February 2002

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  1. An introduction to metadata Metadata : from soup to nuts, NOF-digitise programme seminar,London, 5 February 2002 Email p.johnston@ukoln.ac.uk URL http://www.ukoln.ac.uk/ Pete Johnston UKOLN, University of Bath Bath, BA2 7AY UKOLN is supported by:

  2. An introduction to metadata • What is metadata & what is it used for? • Metadata for resource discovery: introducing the Dublin Core • How is metadata created? • How is metadata shared? • Resource discovery metadata in the NOF-digitise programme Metadata: from soup to nuts, London, 5 Feb 2002

  3. What is metadata & what is it used for?

  4. What is metadata? • “Metadata creation = the art formerly known as cataloguing”? • delivery of resources by resource creators/owners • rather than (or as well as) by intermediary • remote access to resources for all • (potentially…) • emphasis on customer/user • information overload • quantity vs. quality? • the Google effect Metadata: from soup to nuts, London, 5 Feb 2002

  5. What is metadata? (2) • “Data associated with objects which relieves their potential users of having to have full advance knowledge of their existence or characteristics. A user might be a program or a person.” • Dempsey and Heery, 1998 • “Machine understandable information about web resources or other things.” • Berners-Lee, 1997 • Structured data about resources that can be used to help support a wide range of operations Metadata: from soup to nuts, London, 5 Feb 2002

  6. Who/what uses metadata? • Human agent • owner managing resources • researcher seeking resources • third party services • Software agents • aggregators • “portals” presenting “landscape” to user • “brokers” performing query tasks on behalf of user Metadata: from soup to nuts, London, 5 Feb 2002

  7. HTML documents digital images databases books museum objects archival records metadata records collections services physical places people abstract “works” concepts events What resources, objects, things? Metadata: from soup to nuts, London, 5 Feb 2002

  8. What operations? • Different “flavours” of metadata serve different purposes • simple, generic vs. rich, specific • published widely vs. shared within community vs. used by resource owner/manager • Owner / manager / provider wants to • establish control of resources • administer/manage resources (through time) • disclose/promote resources • enable and control access/use of resources • contextualise resources Metadata: from soup to nuts, London, 5 Feb 2002

  9. What operations? (2) • End user wants to • find • identify • select • obtain/use • interpret • Third party service may want to • disclose/promote • enable and control access/use • annotate • re-contextualise Metadata: from soup to nuts, London, 5 Feb 2002

  10. What information required in metadata? • No “one size fits all” solution • Depends on operation which metadata supports • Refer to standards: • Benefit of others’ experience, expertise • Provide basis for good practice • Reflect consensus, so facilitate exchange, access, interoperability • May have support in software tools • “Administrative” metadata Metadata: from soup to nuts, London, 5 Feb 2002

  11. Metadata for resource discovery: introducing the Dublin Core

  12. Resource discovery & metadata • Resource users may wish to • search across descriptions from different providers • compare/combine descriptions from different providers • Resource providers may wish to • disseminate descriptions widely • share descriptions with other providers, 3rd parties • describe relationships between resources • Third parties may wish to • build “services” on descriptions prepared by others • annotate descriptions prepared by others Metadata: from soup to nuts, London, 5 Feb 2002

  13. Resource discovery & metadata • Metadata for resource discovery is • used beyond its creator community • combined with metadata from other communities • Metadata is aggregated or cross-searched • challenge of “semantic interoperability” Metadata: from soup to nuts, London, 5 Feb 2002

  14. Resource discovery metadata • Typically covers • description of resource content • what is it? • may include some description of context • description of resource form • how is it constructed? • description of resource use • what tools do I need to use it? • can I afford it? Metadata: from soup to nuts, London, 5 Feb 2002

  15. Introducing the Dublin Core • Initiative to improve resource discovery on Web • not for complex resource description • simple “document-like objects” • extended to other classes of resource • Interdisciplinary consensus on simple element set • 15 elements • all optional • all repeatable Metadata: from soup to nuts, London, 5 Feb 2002

  16. Title Subject Description Creator Publisher Contributor Date Type Format Identifier Source Language Relation Coverage Rights Introducing the Dublin Core Metadata: from soup to nuts, London, 5 Feb 2002

  17. Introducing the Dublin Core • Simplicity of semantics, ease of use • Provides basic semantic interoperability • across domains • across language communities • Allows for extensibility • but tension between extending DC and choosing other, richer schema Metadata: from soup to nuts, London, 5 Feb 2002

  18. Introducing the Dublin Core • Interoperability requires • use of content rules/standards • clarity about resource being described • e.g. work, expression, manifestation, item • Real resources more complex than (stable) “document-like object”? • characteristics of resources change through time • agents perform actions which produce changes Metadata: from soup to nuts, London, 5 Feb 2002

  19. Using the Dublin Core • Not a replacement for richer descriptive standards • A “pidgin” language for use by “tourists on the Internet commons” • Tom Baker, “A Grammar of Dublin Core” • Can provide 15 “windows” into richer resource descriptions • disclose rich description in simple form • semantic cross-walks, mappings • export rather than create? • NOF-digitise guidelines (5.2.1) mandate generation of simple DC records at item-level Metadata: from soup to nuts, London, 5 Feb 2002

  20. Using the Dublin Core title creator date desc rights Simple DC description Rich description Metadata: from soup to nuts, London, 5 Feb 2002

  21. How is metadata created?

  22. How is metadata created? • By software tools • indexing robots, web crawlers • from resource content, from server info • By human agents • description by resource creator/owner • description by third party services • Creating (and maintaining) good quality metadata is not cheap • rights issues for metadata as well as for resources? Metadata: from soup to nuts, London, 5 Feb 2002

  23. Where is metadata stored? • Embedded in resource • depends on format of resource • can metadata be extracted from resource? • Linked to resource • Created as record in “database” • may be remote database • Adopt approach which offers most flexibility • may need to “present” different subsets of full metadata in different contexts Metadata: from soup to nuts, London, 5 Feb 2002

  24. Metadata embedded in resource Metadata embedded in resource Doc Creator Date Title Creator = J Smith Date = 2001-11-05 Title = Report 1 J Smith 2001-11-05 Report Resource1 Metadata database Metadata: from soup to nuts, London, 5 Feb 2002

  25. Metadata record as linked resource Metadata record as linked resource Doc = 1 Doc Creator Date Title Creator = J Smith Date = 2001-11-05 Title = Report Metadata rec 1 1 J Smith 2001-11-05 Report Metadata rec = 1 Resource 1 Metadata database Metadata: from soup to nuts, London, 5 Feb 2002

  26. Metadata record created in database Metadata record created in database Doc Creator Date Title 1 J Smith 2001-11-05 Report Resource 1 Metadata database Metadata: from soup to nuts, London, 5 Feb 2002

  27. How is metadata shared?

  28. How is metadata shared? • How does a data provider make metadata records available in a commonly understood form? • How does a service provider obtain these metadata records from data providers? Metadata: from soup to nuts, London, 5 Feb 2002

  29. How is metadata shared? • Metadata as language; metadata records as sets of statements • Effective transmission of information requires agreement on • semantics • what terms mean • e.g. “cat”, “to sit”, “mat” • structure • significance of arrangement of terms • e.g. sentence: subject -> verb -> object (in English….) • syntax • rules of expression • “The cat sat on the mat.” Metadata: from soup to nuts, London, 5 Feb 2002

  30. How is metadata shared? • A resource description community is defined by consensus on conventions • Consensus on syntax • use of XML • Consensus on semantics of terms • meaning of (uniquely named through XML namespace) elements/attributes • Consensus on meaning of structure • use of community standard XML DTD/Schema Metadata: from soup to nuts, London, 5 Feb 2002

  31. Introducing XML • Extensible Markup Language • Recommendation of W3C, 1998, 2000 • Defines means of describing tree-structured data in text-based format • embedded markup delimits and describes data • Simple, platform-independent syntax • Standard programming interfaces • reusable software components • Widely adopted for transferring data between programs, systems Metadata: from soup to nuts, London, 5 Feb 2002

  32. table record record creator date doc title J Smith 2001-11-05 1 Report Doc Creator Date Title 1 J Smith 2001-11-05 Report <table> <record> <doc>1</doc> <creator>J Smith</text> <date>2001-11-05</date> <title>Report</title> </record> </table> Metadata: from soup to nuts, London, 5 Feb 2002

  33. Doc Creator Date Title Serialisation <record> ... </record> Transmission <record> ... </record> Remote application De-serialisation Metadata: from soup to nuts, London, 5 Feb 2002

  34. Introducing XML (2) • Support from major software vendors • Use of XML • invisible to end-user • increasingly invisible to information manager? • generated and consumed by software • requires consensus on structure amongst communication partners • Use XML for exchange when • partners (humans, applications) both “know” semantics conveyed by structure of (meta)data • Use RDF/XML for exchange when • (meta)data potentially used by applications without prior “knowledge” of specific schema • (meta)data incorporates overlapping structures from different domains Metadata: from soup to nuts, London, 5 Feb 2002

  35. Introducing OAI • Open Archives Initiative • develops/promotes interoperability standards to facilitate dissemination of content • roots in e-prints community • “Archive” = repository, not archive • “Open” in terms of architecture, not free/unlimited access to repository Metadata: from soup to nuts, London, 5 Feb 2002

  36. Introducing OAI MHP • OAI Metadata Harvesting Protocol • lightweight protocol which allows data providers to expose metadata records for retrieval by service providers • built on HTTP, XML • requests from service provider to data provider sent using HTTP GET/POST • Six verbs • responses from data provider to service provider as XML documents • Must provide simple DC (OAI provides XML Schema) • May provide other metadata formats (in XML) Metadata: from soup to nuts, London, 5 Feb 2002

  37. Introducing OAI MHP (2) • Supports selective harvesting • by sets • by datestamps • Example • http://www.myarchive.org/cgi-bin/oai?verb=ListRecords&from=2002-01-01&metadataPrefix=oai_dc • List all records added since Jan 1 2002 in oai_dc format (simple DC) • Returns XML document containing records • OAI MHP is not a distributed search protocol Metadata: from soup to nuts, London, 5 Feb 2002

  38. Resource discovery metadata in the NOF-digitise programme

  39. Web site Metadata Resource discovery within a project Resources Metadata: from soup to nuts, London, 5 Feb 2002

  40. Web site DC export OAI MHP Metadata NOF Portal Web site Web site Resource discovery across the programme Metadata: from soup to nuts, London, 5 Feb 2002

  41. NGfL Portal Web site Web site DC OAI MHP Metadata NOF Portal Web site OAI MHP DNER Portal Web site Web site Resource discovery: the larger context Metadata: from soup to nuts, London, 5 Feb 2002

  42. N.B. …. • N.B. Previous diagrams should be treated as illustration of potential, not description of architecture! • Role of collection-level description in disclosing existence of collections/repositories to portals Metadata: from soup to nuts, London, 5 Feb 2002

  43. Summary • Metadata for resource discovery and resource management • Resource discovery metadata made to be shared • Communication: syntax, semantics, structure • Role of standards • Lightweight protocols for metadata exchange • balance functionality and cost • Enhance access to your project’s resources Metadata: from soup to nuts, London, 5 Feb 2002

  44. 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/ Metadata: from soup to nuts, London, 5 Feb 2002

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