Linked Data Overview - AGI Technical SIG


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An overview of Linked Data (from an outsider's point of view!). Given at AGI Technical SIG event on 22nd November 2011

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Linked Data Overview - AGI Technical SIG

  1. 1. Linked Data – An Overview Chris Ewing 22 nd November 2011
  2. 2. Summary <ul><li>What is Linked Data? </li></ul><ul><li>Why is it useful? </li></ul><ul><li>Geo Examples </li></ul>
  3. 3. What is Linked Data? <ul><li>A method of publishing structured data so that it can be interlinked and become more useful </li></ul><ul><li>Builds upon existing web technologies (HTTP, URI) </li></ul>
  4. 4. The semantic web <ul><li>Linked Data is part of the semantic web (also nicknamed the Giant Global Graph (GGG)) </li></ul><ul><li>Semantic Web describes: </li></ul><ul><ul><li>Relationships between things </li></ul></ul><ul><ul><li>Properties of things </li></ul></ul> The Semantic Web Stack
  5. 5. Linked Data - Timeline <ul><li>Basics have been around since birth of internet </li></ul><ul><li>Tim Berners-Lee paper in 2006 </li></ul><ul><li>TED talk by TB-L in 2009 </li></ul><ul><li>TB-L appointed UK Gov advisor to opening up Government data – Spring 2009 </li></ul><ul><li> launches 2010 </li></ul><ul><li>UK Location Linked Data workshop – Sep 2010 </li></ul><ul><li>This workshop today! </li></ul>
  6. 6. Why is it useful? <ul><li>Linked Data allows you to discover, connect to, describe, and re-use all kinds of data </li></ul><ul><li>Better answers to searches etc. </li></ul>
  7. 7. Why is it useful? <ul><li>Can combine ALL kinds of data in a similar environment , share ACROSS organisations & reuse data and links </li></ul><ul><li>Faster access to data </li></ul><ul><li>More relevant data returned </li></ul>
  8. 8. Linked Data - Rules <ul><li>Rule 1 – put something on the web </li></ul><ul><ul><li>Not just docs, but people, places too </li></ul></ul><ul><li>Rule 2 – get information back </li></ul><ul><ul><li>Data in a useful format </li></ul></ul><ul><li>Rule 3 – data is relationships </li></ul><ul><ul><li>e.g. I was born in Liverpool, Liverpool is in Merseyside </li></ul></ul>
  9. 9. Rule 1 - on the web <ul><li>In the beginning only documents on the web </li></ul><ul><li>Now also music, video, maps, people, places etc. </li></ul>
  10. 10. Rule 2 – get information back <ul><li>Ask a question and get a useful response </li></ul><ul><li>Show me all railways from OS 50k gazetteer </li></ul>1. Search 2. Results 3. Items
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  14. 14. Rule 3 – Data is Relationships <ul><li>Postcode SO16 4GU is within SO16 4 </li></ul><ul><li>SO16 4 is within SO16 </li></ul><ul><li>SO16 is within SO </li></ul><ul><li>SO is within City of Southampton </li></ul><ul><li>Etc. </li></ul>
  15. 15. Linked Data “Rating” 2010 - ★ Available on the web (whatever format), but with an open licence ★★ Available as machine-readable structured data (e.g. excel instead of image scan of a table) ★★★ as (2) plus non-proprietary format (e.g. CSV instead of excel) ★★★★ All the above plus, Use open standards from W3C (RDF and SPARQL) to identify things, so that people can point at your stuff ★★★★★ All the above, plus: Link your data to other people’s data to provide context
  16. 16. Linked Data Acronyms
  17. 17. URI <ul><li>Uniform Resource Identifier </li></ul><ul><li>String of characters used to reference a name or a resource on the Internet </li></ul><ul><li>Names for things! </li></ul><ul><li> </li></ul><ul><li>// </li></ul><ul><li>relative/path/to/resource.txt </li></ul><ul><li>../../../resource.txt </li></ul><ul><li>./resource.txt#frag01 </li></ul><ul><li>resource.txt </li></ul><ul><li>#frag01 </li></ul>
  18. 18. RDF <ul><li>Resource Description Framework </li></ul><ul><li>RDF uses URI references to identify resources and properties </li></ul><ul><li>“ The sky has the colour blue&quot; in RDF is as the triple: </li></ul><ul><ul><li>a subject denoting &quot;the sky&quot; </li></ul></ul><ul><ul><li>a predicate denoting &quot;has the colour&quot; </li></ul></ul><ul><ul><li>an object denoting &quot;blue“ </li></ul></ul>* RDF Triple
  19. 19. OWL <ul><li>OWL Web Ontology Language </li></ul><ul><li>describes the meaning of terminology in web documents </li></ul>
  20. 20. SPARQL <ul><li>SPARQL - SPARQL Protocol and RDF Query Language </li></ul><ul><li>Query the resources </li></ul><ul><li>PREFIX foaf: <> </li></ul><ul><li>SELECT ?name ?email </li></ul><ul><li>WHERE { </li></ul><ul><li>?person a foaf:Person. </li></ul><ul><li>?person foaf:name ?name. </li></ul><ul><li>?person foaf:mbox ?email. </li></ul><ul><li>} </li></ul>e.g. Returns Name and Email of everyone in a dataset
  21. 21. GeoSPARQL <ul><li>Geospatial version of SPARQL </li></ul><ul><li>Created by an OGC working group </li></ul><ul><li>Goal is to “ support representing and querying geospatial data on the Semantic Web ” </li></ul><ul><li>Standardisation vote at end of 2011 </li></ul><ul><li>Example – Select Airports near London </li></ul>
  22. 22. Some examples <ul><li>GeoNames </li></ul><ul><li> </li></ul><ul><li>Ordnance Survey </li></ul><ul><li>DNF </li></ul><ul><li>INSPIRE </li></ul><ul><li>UK Location </li></ul>
  23. 23. GeoNames <ul><li>makes it possible to add geospatial semantic information to the Word Wide Web. </li></ul><ul><li>Features in the GeoNames Semantic Web are interlinked with each other </li></ul><ul><li>All starts with Mother Earth </li></ul><ul><li>RDF dump with 7857409 features with 145919822 RDF triples (2011 08 24) </li></ul>
  24. 24. <ul><li> </li></ul><ul><li>A series of SPARQL end points let you query the different data sources </li></ul>
  25. 25. Ordnance Survey Linked Data <ul><li> </li></ul><ul><li>3 Linked Data datasets so far: </li></ul><ul><ul><li>Postcodes </li></ul></ul><ul><ul><li>50k Gazeetter </li></ul></ul><ul><ul><li>Administrative boundaries </li></ul></ul><ul><li>Free Text Search - </li></ul>
  26. 26. DNF / UK Location <ul><li>Digital National Framework </li></ul><ul><li>Oct 2011 – new Linked Data subgroup at BCS </li></ul><ul><li>EA bathing waters example from BSI Geographic Standards Committee* </li></ul><ul><li>UKLocation / BCS Linked Data business benefits – this Thursday 24 th Nov at BCS offices </li></ul>*
  27. 27. *
  28. 28. INSPIRE and Linked Data *
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  30. 30. Chris Ewing Impact Forecasting Aon Benfield Analytics t: +44 (0)207 522 8305 e: [email_address] twitter: @web_gis
  31. 31. References <ul><li>Linked Data </li></ul><ul><ul><li> </li></ul></ul><ul><ul><li> </li></ul></ul><ul><ul><li> </li></ul></ul><ul><li>RDF </li></ul><ul><ul><li> </li></ul></ul><ul><li>SPARQL </li></ul><ul><ul><li> </li></ul></ul><ul><li>GeoSPARQL </li></ul><ul><ul><li> </li></ul></ul><ul><li>Ordnance Survey Linked Data </li></ul><ul><ul><li> </li></ul></ul><ul><ul><li> </li></ul></ul><ul><li> LinkedData </li></ul><ul><ul><li> </li></ul></ul><ul><li>Linked Data and INSPIRE </li></ul><ul><ul><li> </li></ul></ul><ul><ul><li> </li></ul></ul>