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Linked Data and the Semantic Web: What Are They and Should I Care?


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Presentation for UKOLN staff seminar in the library at the University of Bath, 5th November 2009

Published in: Technology, Education
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Linked Data and the Semantic Web: What Are They and Should I Care?

  1. 1. UKOLN is supported by: Linked Data and the Semantic Web - What are they and should I care? 6 th November 2009 UKOLN Staff Seminar, University of Bath, UK Adrian Stevenson
  2. 2. <ul><li>semantics is … devoted to the study of meaning … on the syntactic levels of words, phrases, sentences </li></ul><ul><li> </li></ul>
  3. 3. <ul><li>“ The Semantic Web is a web of data , in some ways like a global database” 1 </li></ul><ul><li>“ first step is putting data on the Web in a form that machines can naturally understand...  This creates what I call a Semantic Web - a web of data that can be processed directly or indirectly by machines” 2 </li></ul><ul><li>1. </li></ul><ul><li>2. Tim Berners-Lee, Weaving the Web . Harper, San Francisco. 1999. </li></ul>
  4. 4. <ul><li>“ The term Linked Data refers to a set of best practices for publishing and connecting structured data on the Web.” </li></ul><ul><li>“ the Semantic Web is the goal or end result… Linked Data provides the means to reach that goal” </li></ul><ul><li>From ‘ Linked Data: The Story So Far ’ - Heath, Bizer and Berners-Lee 2009 </li></ul>
  5. 5. The Web We’re Used To <ul><li>Made by humans for humans </li></ul><ul><li>Primarily documents </li></ul><ul><li>Machines not very welcome </li></ul><ul><li>Data silos </li></ul>
  6. 6. Web of Linked Data <ul><li>In 1998 the idea from Tim Berners-Lee of ‘linked data’ took shape </li></ul><ul><li>Designed for machines first </li></ul><ul><li>It primarily links data about ‘things’, not documents </li></ul><ul><li>… but it is for humans in the end </li></ul>
  7. 7. <ul><li>But haven’t we been putting data on the web for years? </li></ul><ul><ul><li>In CSV , relational databases, XML etc? </li></ul></ul><ul><li>Well yes, but these approaches are not so easy to integrate </li></ul><ul><li>Web 2.0 mashups work against a fixed set of data sources </li></ul><ul><li>Linked Data applications operate on top of an unbound, global data space. </li></ul>
  8. 8. So what’s happening now?
  9. 10. <ul><li>“ Sir Tim Berners-Lee, the inventor of the world wide web, will help the British government to make its data more easily available online … I have asked Sir Tim Berners-Lee … to help us drive the opening up of access to Government data in the web” Prime Minister Gordon Brown, 10 th June 2009 </li></ul><ul><li>&quot;What you find if you deal with people in government departments is that they hug their database, hold it really close”. Tim Berners-Lee, 10 th June 2009 </li></ul><ul><li>We shall see … </li></ul>
  10. 12.
  11. 15. BBC Music BETA
  12. 20. A little bit of the techy stuff
  13. 21. Linked Data is … <ul><li>A way of publishing data on the web that: </li></ul><ul><ul><li>Encourages reuse </li></ul></ul><ul><ul><li>Reduces redundancy </li></ul></ul><ul><ul><li>Maximises inter-connectedness </li></ul></ul><ul><ul><li>Enables network effects </li></ul></ul><ul><li>So how is this achieved? </li></ul>
  14. 22. Presentational tagging – HTML <ul><li><h1>Agilitas Physiotherapy Centre</h1> <p>Welcome to the Agilitas Physiotherapy Centre home page. Do you feel pain? Have you had an injury? Let our staff Lisa Davenport, our secretary Kelly Townsend, and Steve Matthews take care of your body and soul.</p> <h2>Consultation hours</h2> Mon 11am - 7pm<br/> Tue 11am - 7pm<br/> Wed 3pm - 7pm<br/> Thu 11am - 7pm<br/> Fri 11am - 3pm </li></ul><ul><li><p> But note that we do not offer consultation during the weeks of the <a href=&quot;. . .&quot;>State Of Origin</a> games.</p> </li></ul>
  15. 23. Semantic tagging <ul><li><company> </li></ul><ul><li><treatmentOffered>Physiotherapy</treatmentOffered> </li></ul><ul><li><companyName>Agilitas Physiotherapy Centre</companyName> </li></ul><ul><li><staff> </li></ul><ul><li><therapist>Lisa Davenport</therapist> <therapist>Steve Matthews</therapist> </li></ul><ul><li><secretary>Kelly Townsend</secretary> </li></ul><ul><li></staff> </li></ul><ul><li></company> </li></ul>
  16. 24. Tim BL’s Linked Data Design Issues <ul><li>Use URIs as names for things </li></ul><ul><li>Use HTTP URIs so that people can look up those names. </li></ul><ul><li>When someone looks up a URI, provide useful information, using the standards (RDF, SPARQL) </li></ul><ul><li>Include links to other URIs so that they can discover more things. </li></ul><ul><li>From </li></ul>
  17. 25. URIs and HTTP <ul><li>A “Uniform Resource Identifier (URI) provides a simple and extensible means for identifying a resource –RFC 3986 </li></ul><ul><ul><li>A URL is a type of URI </li></ul></ul><ul><ul><li>HTTP URIs can be ‘de-referenced’ </li></ul></ul><ul><li>HTTP URIs are used for “real world” things </li></ul><ul><ul><li> </li></ul></ul><ul><ul><li> </li></ul></ul>
  18. 26. RDF <ul><li>Resource Description Framework </li></ul><ul><ul><li>“ a language for representing information about resources in the World Wide Web” </li></ul></ul><ul><ul><li>“ RDF can also be used to represent information about things that can be identified on the Web, even when they cannot be directly retrieved on the Web” </li></ul></ul><ul><li>Describes relations based on triples </li></ul><ul><ul><li>S ubject-object-predicate </li></ul></ul><ul><li> </li></ul>
  19. 27. <ul><li>Heroes </li></ul><ul><li>has a </li></ul><ul><li>creator </li></ul><ul><li> whose name is </li></ul><ul><li>David Bowie </li></ul>Subject Predicate Object
  20. 28. Linked Data in Use
  21. 29. Publishing Linked Data <ul><li>RDFizers – convert data formats into RDF </li></ul><ul><li>D2R Server – creates linked data from relational databases </li></ul><ul><li>SparqPlug – Extracts linked data from HTML </li></ul><ul><li>… . Many others </li></ul>
  22. 32. Linked Data Applications <ul><li>Linked Data Browsers – navigate between data sources </li></ul><ul><ul><li>Disco </li></ul></ul><ul><ul><li>Tabulator </li></ul></ul><ul><ul><li>Marbles </li></ul></ul><ul><li>Linked Data Search Engines </li></ul><ul><ul><li>For humans – Falcons, SWSE </li></ul></ul><ul><ul><li>For apps – Swoogle, Sindice </li></ul></ul>
  23. 33. <ul><li>Tracks provenance of data </li></ul><ul><li>Merges data about the same thing from different sources </li></ul>
  24. 34. <ul><li>User can explore the underlying data structures </li></ul><ul><li>Can search for objects, concepts or documents </li></ul>
  25. 35. <ul><li>Provides interface (API) that other linked data apps can use </li></ul><ul><li>Rationale: new linked data apps shouldn’t need to implement their own infrastructure for crawling and indexing web of data </li></ul>
  26. 36. Some issues <ul><li>To RDF or not to RDF </li></ul><ul><li>Usability </li></ul><ul><li>Sustainability </li></ul><ul><li>Provenance </li></ul><ul><li>Licensing </li></ul><ul><li>Reliability </li></ul>
  27. 37. I Linked Data Therefore I RDF
  28. 44. Sustainability <ul><li>Ed Summers at the Library of Congress created </li></ul><ul><li>Linked Data interface for LOC subject headings </li></ul><ul><li>People started using it </li></ul>
  29. 45. Library of Congress Subject Headings
  30. 47. Data Licensing <ul><li>RDF Book Mashup </li></ul><ul><li>makes information about books, their authors, reviews, and online bookstores available on the Semantic Web </li></ul><ul><li>Uses Amazon Web Services but contravenes terms and conditions </li></ul>
  31. 48. Provenance <ul><li>OK if data ‘watermarked’ </li></ul><ul><li>But can often be a problem </li></ul><ul><li>VOID can help (apparently!) </li></ul>
  32. 49. Woolyish conclusion <ul><li>Some interesting recent developments and sense of momentum </li></ul><ul><li>Central Gov’t interested </li></ul><ul><li>… but still much to do if the semantic web and linked data are to really take hold </li></ul>
  33. 50. Questions? <ul><li> </li></ul><ul><li>[email_address] </li></ul>
  34. 51. CC Attribution <ul><li>Some sections of this presentation adapted from: </li></ul><ul><ul><li>An Introduction to Linked Data , by Tom Heath </li></ul></ul><ul><ul><li>The Semantic Web – An Introduction by Owen Stephens </li></ul></ul><ul><ul><li>Using Linked Data as a Learning Resource Recommendation System by Chris Clarke </li></ul></ul><ul><li>This presentation available under creative commons Noncommercial-Share Alike </li></ul>