A short introduction to Linked Data, for project meeting of Bricolage project, ILRT, Bristol, Thursday 26 Jan 2012

1. Linked Data
A short(-ish) introduction
Bricolage Project meeting, Bristol, 26 Jan 2012
Pete Johnston
Technical Researcher, Eduserv
pete.johnston@eduserv.org.uk

2. Document Web Principles
• Use URIs as names of documents
• Use http URIs, so that people can use HTTP protocol to
look up those names
• When someone looks up a URI, provide the document
(*)
• Use document standards, e.g. HTML
• Include links to other documents, so that people can
discover more documents

3. Use URIs as names of documents
http://en.wikipedia.org/wiki/D.H._Lawrence

4. Use http URIs…
http://en.wikipedia.org/wiki/D.H._Lawrence

5. Provide the documents

6. Use document standards

7. Include links to other docs
• Links typically “untyped”
<a href="/wiki/Eastwood,_Nottinghamshire"
title="Eastwood, Nottinghamshire">Eastwood</a>
<a href="/wiki/Lady_Chatterley%27s_Lover" title="Lady
Chatterley's Lover">Lady Chatterley's Lover</a>
<a href="/wiki/Joseph_Conrad"
title="Joseph Conrad">Joseph Conrad</a>
 Occasionally “typed”
<link rel="copyright“
href=“http://creativecommons.org/licenses/by-sa/3.0/" />

8. (*) On “providing the document”: content negotiation
• Client HTTP request for doc includes info about
preferences, e.g.
• Language (Prefer English, but will accept Spanish)
• Media-type (Prefer XHTML, but will accept
HTML, plain text)
• Server responds with representation of doc which best
matches preferences

9. Linked Data Principles (a version!)
• Use URIs as names of things
• people, places, concepts, documents… anything!
• (avoid URI ambiguity)
• Use http URIs so that people and programs can look up
those names
• When a person or program looks up a name, provide
(representations of) documents about the things

10. Linked Data Principles (a version!)
 Use data standards: RDF
 Include typed links to other things
 so that people and programs can discover other
things

11. Use URIs as names of things
http://dbpedia.org/resource/D.H._Lawrence

12. Use http URIs…
http://dbpedia.org/resource/D.H._Lawrence

13. Provide documents about those things…
Thing:
http://dbpedia.org/resource/D.H._Lawrence
Document:
http://dbpedia.org/page/D.H._Lawrence

14. …with representations suitable for people…

15. …and representations suitable for programs

16. Use data standards: RDF
• A way to model data
• Assertions of relationships between two things
• Triples: subject, predicate, object
DH Lawrence
has-notable-work
Lady Chatterley's Lover

17. Use data standards: RDF
• Triples: use URIs as “words”/names
<http://dbpedia.org/resource/D._H._Lawrence>
<http://dbpedia.org/ontology/notableWork>
<http://dbpedia.org/resource/Lady_Chatterley%27s_
Lover>
• In RDF syntaxes, URIs often abbreviated
• dbpedia:D._H._Lawrence

18. Use data standards: RDF
• Extensibility of vocabulary
• Reuse of vocabulary
• “Self-description”
• vocabulary terms described using RDF
• Rules for data merging/integration
• “Formal semantics”, basis for inferencing

19. Include typed links to other things
dbpedia:D._H._Lawrence
dbp-owl:birthPlace
dbpedia:Eastwood,_Nottinghamshire ;
dbp-owl:notableWork
dbpedia:Lady_Chatterley%27s_Lover ;
dbp-owl:influencedBy
dbpedia:Joseph_Conrad .

20. “Linked data is data you can click on”
(?John Sheridan, National Archives)

21. Linked Data from British Library: D. H. Lawrence

22. Linked Data from OCLC VIAF: D. H. Lawrence

23. Linked Data from Freebase: D. H. Lawrence

24. Linked Data from BBC:
Programmes related to D. H. Lawrence

25. Archives Hub EAD data: D. H. Lawrence letters

26. Sindice/Sig.ma: RDF data aggregator/search

27. RDF & Linked Data: some strengths/features
• Designed for the Web, “open world”
• Anyone can say anything about anything
• No-one says everything about anything
• Extensible, decentralised
• Rules for data merging/integration
• Inferencing

28. RDF & Linked Data: Some challenges
 New concepts, formats, tools
 (Re)modelling/migration/conversion
 Linking & identity
 Versioning & time
 Trust

29. How?
• Model our “world”
• Design URI patterns
• Select/create RDF vocabularies
• Convert/transform data
• Generate links
• Publish/expose data

30. Acknowledgements / some useful sources
• Tom Heath & Chris Bizer, Linked Data: Evolving the Web into a Global Data
Space
http://linkeddatabook.com/
• Yves Raimond & Michael Smethurst, “A skim-read introduction to linked data”
http://www.bbc.co.uk/blogs/radiolabs/s5/linked-data/s5.html
• Dave Reynolds, “Linked data and its role in the semantic web”
http://www.slideshare.net/der42/introduction-to-linked-data-and-the-semantic-
web-8700415

31. Linked Data
A short(-ish) introduction
Bricolage Project meeting, Bristol, 26 Jan 2012
Pete Johnston
Technical Researcher, Eduserv
pete.johnston@eduserv.org.uk