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Gordon Dunsire

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  1. Linked data and the implications for library cataloguing: metadata models and structures in the Semantic Web Gordon Dunsire Presented at the Canadian Library Association Annual Conference, 26-29 May 2011, Halifax, Nova Scotia

  2. Outline • Context: evolution of the catalogue record • RDF 101 • Library metadata models/schemas in RDF • FRBR, RDA, ISBD, DCT, BiBO, ... • From record to triples: worked example

  3. A short historyof the evolutionof the library catalogue record

  4. In the beginning ... Lee, T. B. Cataloguing has a future. - Audio disc (Spoken word). - Donated by the author. 1. Metadata ... the catalogue card

  5. From flat-file record ... Bibliographic description Name authority Author: Lee, T. B. Name: Biography: Title: Cataloguing has a future ... Content type: Spoken word Carrier type: Audio disc Subject authority Subject: Metadata Term: Provenance: Donated by the author Definition: ... ... to relational record

  6. From flat-file description ... Bibliographic description Name authority Author: Name: Lee, T. B. Biography: Title: Cataloguing has a future ... Work Content type: Spoken word Author: Carrier type: Audio disc Subject authority Subject: Subject: Term: Metadata Expression Provenance: Donated by the author Definition: Content type: Spoken word ... Manifestation Item ... to FRBR record

  7. From FRBR record ... Work Name authority Author: Name: Lee, T. B. Subject: Subject authority Expression Term: Metadata Content type: Spoken word Manifestation RDA content type Title: Cataloguing has a future Term: Carrier type: Audio disc RDA carrier type Item Term: Provenance: Donor: Donated by the author Amazon/Publisher Title: ... to extinction!

  8. Where is the record? • Implicit, not explicit • Everywhere and nowhere • A semantic Web will allow machines to create the record just-in-time • We will not have to maintain records just-in-case • The user will have control over the presentation • I want to see an archive or library or museum or Amazon or Google or Flickr or ? display • And by avoiding duplication, we can all get on with describing new stuff ...

  9. The hyperdimensional (Tardis) card W3C Library Audio shop Lee, T. B. Cataloguing has a future. - Audio disc (Spoken word). - Donated by the author. 1. Metadata Lee Museum Spoken word archive “TARDIS four port USB hub, for office-bound Time Lords: Open a time vortex on your desk” – Pocket-lint

  10. RDF 101

  11. Semantic Web • “machine-readable metadata” • Faster! 24/7/365! Global! • Metadata expressed as “atomic” statements • A simple, single, irreducible statement • The title of this book is “Treasure island” • In a standard machine-processable format • Resource Description Framework (RDF)

  12. Resource Description Framework • Metadata statement constructed in 3 parts • “Triple” • The title of this book is “Treasure island” • Subject of the statement = Subject: This book • Nature of the statement = Predicate: has title • Value of the statement = Object: “Treasure island” • This book – has title – “Treasure island” • subject – predicate - object

  13. Identifiers • Need unambiguous way of identifying each part of the triple for efficient machine-processing • Human labels (“This book”, “has title”) no good • Same thing, different labels; different things, same label • Exploit the utility of the URL • Machine-readable, regular syntax, unambiguous • Uniform Resource Identifier (URI)

  14. Uniform Resource Identifier • Can be any unique combination of numbers and letters • No intrinsic meaning; it’s just an identifying label • Can look like a URL • http://iflastandards.info/ns/isbd/elements/P1001 • But does not lead to a Web page (in principle ...) • RDF requires the subject and predicate of triple to be URIs • Object can be a URI, or a literal string (“Treasure island”)

  15. Namespaces • URI can be constructed from a base plus a unique, identifying suffix • http://iflastandards.info/ns/isbd/elements/ • + P1001 • Base is known as a namespace • Can be abbreviated by human programmer • “isbd” = http://iflastandards.info/ns/isbd/elements/ • isbd:P1001 • Machine expands abbreviation for processing

  16. Everything as triples in RDF • Every aspect of the metadata must be expressed in RDF to be machine-processable • Metadata about real-world objects (books, people, etc.) • Metadata about the predicates (definition, label, scope, etc.) • Common predicates apply to many types of thing (human-readable label, etc.) • High-level RDF namespaces (rdfs, owl) • RDF is expressed in RDF (“bootstrap”)

  17. Library namespaces

  18. Creating namespaces and URIs • FRBR/FRAD/FRSAD, ISBD, and RDA are using the Open Metadata Registry • Can assign a running “number” to the base to create a new URI • Set of properties for creating basic triples • Properties = predicates • rdfs:label for assigning a human-readable label to the subject • isbd:P1001 - rdfs:label - “has content form”

  19. Subject Predicate Object isbd:P1001 rdfs:label “has content form”

  20. Subject Predicate Object isbdcf:T1008 skos:prefLabel “spoken word”

  21. Application profile • Need a way to specify how a useful “record” can be constructed from RDF triples • Which triples are involved, and from which namespaces? • Sequence? Repeatable? Mandatory? • Sub-component aggregations • Publication statement = place + name + date • Content rules?

  22. Mandatory Not repeatable Aggregation of simpler elements Syntax of aggregation (punctuation)

  23. Getting triples from records

  24. Linking Open Data cloud (LOD) Diagram by Richard Cyganiak and AnjaJentzsch. http://lod-cloud.net/

  25. LOD: “Library” corner

  26. Why get involved? • To share our data • We work for “society” • To share our expertise and experience • 150 + years • To promote the power of libraries (and archives and museums) • To survive

  27. From record to triples (in 9 stages) • Very large numbers of records • Catalogue records, finding aids, etc. • 300 million; 1 billion? • High quality metadata • In comparison with other communities • Each record may generate many triples • 200 “raw” triples (no inferences) per MARC record? • Very, very large numbers of triples • Billions? Trillions?

  28. 1. Take a record

  29. 2. Disaggregate to single statements

  30. 3. Create URI for record • Must be unique, so 54321 no good on its own • http URIs are a good thing (W3C) • So add record ID to a unique http domain • E.g. http://MyLibraryX.com (unique to the library) • + 54321 • http://MyLibraryX.com/54321 • (or http://MyLibraryX.com#54321) • This is not a URL!

  31. 4. Replace record ID with URI “mlx” = qname (xmlns) = shorthand for “http://MyLibraryX.com/”

  32. 5. Find URIs for attributes • Attributes are modelled as RDF properties (predicates) in “element set” namespaces • E.g. Dublin Core terms (dct); ISBD (isbd); FRBR (frbrer); RDA (rdaxxx); Bibliographic Ontology (bibo); etc. • Choose a namespace, find property with same (or closest) “meaning” (e.g. definition) as attribute • Nearest property minimises loss of information • Get URI for property • If no suitable property, choose another namespace • Properties do not have to come from single namespace • Match and mix!

  33. 5 (cont). Find URI for title • http://purl.org/dc/terms/title (dct:title) • http://iflastandards.info/ns/isbd/elements/P1014 (isbd:P1014) • hasTitleProper • http://RDVocab.info/Elements/titleProper  (rdaGR1:titleProper)

  34. 5 (cont). Find URI for author • dct:creator • rdarole:author • (isbd does not cover “headings”)

  35. 5 (cont). Find URI for date • dct:date • isbd:P1018 • hasDateOfPublicationProductionDistribution • rdaGr1:dateOfPublication

  36. 5 (cont). Find URI for LCSH • LCSH is a subject vocabulary • Controlled terms • So attribute is really “subject” • And the term itself is the value • dct:subject

  37. 5 (cont). Find URI for media type • Assuming record uses new ISBD Area 0 ... • isbd:P1003 • hasMediaType

  38. 5 (cont). Find URI for content form • Assuming record uses new ISBD Area 0 ... • isbd: P1001 • hasContentForm

  39. 6. Replace attributes with URIs

  40. 7. Find URIs for values • If object of a triple is a URI, it can link to the subject of another triple with the same URI • Linked data! • Values from controlled vocabularies may have URIs • Possible vocabularies: author, subject, ISBD Area 0 • NOT: title, date • For author: Virtual International Authority File (VIAF) • For LCSH: Library of Congress Authorities & Vocabularies • For ISBD Area 0: Open Metadata Registry