An introduction to RDF and library linked data

1. An introduction to RDF and library linked data Gordon Dunsire Presented at the Dewey Decimal Classification Executive Briefing 15 Sep 2011, London

2. Semantic Web • “machine-readable metadata” • Faster! 24/7/365! Global! • In a standard machine-processable format • Resource Description Framework (RDF) • RDF supports simple, single metadata statements known as triples • Each statement is in 3 parts

3. RDF triple • The title of this book is “Physics is fun” • Subject of the statement = Subject: This book • Nature of the statement = Predicate: (has) title • Value of the statement = Object: “Physics is fun” • This book – has title – “Physics is fun” • subject – predicate – object • This presentation – has author – Gordon Dunsire • This seminar – has subject – DDC:025.431

4. 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, global • Uniform Resource Identifier (URI)

5. 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/P1004 • 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 (“Physics is fun”)

6. Identifying library metadata • Represent library schema attributes and relationships as RDF properties (= predicates) • Each property has own URI (from namespace) • Resource Description and Access (RDA), International Standard Bibliographic Description (ISBD), Functional Requirements for Bibliographic Records (FRBR), etc. • Assign URIs to specific library resources • The things described in catalogues • Books, a-v materials, digital resources, etc. • The terms used to describe them • Vocabularies, subject headings, classifications, etc.

7. hasTitleURI BookURI “Physics is fun” BookURI hasAuthorURI JimJardineURI JimJardineURI JimJardineURI PlaceURI hasCoordinatesURI hasBirthPlaceURI hasNNameURI “Jardine, Jim” “abcxyz” PlaceURI has author This book “Physics is fun” has title Jim Jardine hasDDCURI BookURI ddc530URI

8. BookURI hasTitleURI “Physics is fun” “Fiosaigs” ddc530URI “Physics” DDC caption This book title “Physics is fun” location author birthplace Jim Jardine coordinates “abcxyz” “Jardine, Jim” Place X normalised name

9. Library linked data in RDF • Machine-match URIs of triple subjects to obtain set of statements about one thing • A “record” for that thing • Information resource or something associated with it • Machine-match object URI of one triple to subject URI of another to obtain chain of connected statements • Linked data chain can lead to data from outside of library community

10. Benefits of linked data to libraries • Use of data created and maintained by others • Global scale • Sharing of high-quality metadata created by libraries (trillions of triples) • Bibliographic records; authority files • Statement-level granularity allows flexible display of metadata to suit user requirements • Chains go both ways, leading users from external environments to library collections

11. Thank you • W3C Library Linked Data Incubator Group • Final report available via wiki: • http://www.w3.org/2005/Incubator/lld/wiki/Main_Page • gordon@gordondunsire.com