Web of data


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Introduction session to the WOD-PD event in Vienna http://www.webofdata.info/

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Web of data

  1. 1. <ul><li>Web of Data 101 </li></ul><ul><li>Keith Alexander (Talis) </li></ul><ul><li>Yves Raimond (QMUL/BBC A&Mi) </li></ul><ul><li>WOD-PD 2008, October 22 nd , 2008 </li></ul>
  2. 2. Outline <ul><li>Introduction to linked data </li></ul><ul><li>1 st hacking session </li></ul><ul><li>SPARQL </li></ul><ul><li>2 nd hacking session </li></ul><ul><li>What's out there? </li></ul>
  3. 3. The Web of Data
  4. 4. The Web <ul><li>Names (URIs) </li></ul><ul><li>Documents (HTML, XML, JSON, ...) </li></ul><ul><li>Interactions with names (HTTP) </li></ul>Names Documents HTTP GET
  5. 5. Links
  6. 6. What does it look like, now? <ul><li>Names identify documents, e.g. HTML, XML, etc. </li></ul><ul><li>Documents are interlinked: </li></ul><a href=” http://moustaki.org/ ” />
  7. 7. Web of documents
  8. 8. We understand...
  9. 9. We understand...
  10. 10. Machines don't...
  11. 11. Shortcomings <ul><li>Untyped links </li></ul><ul><ul><li>Friend? </li></ul></ul><ul><ul><li>City? </li></ul></ul><ul><ul><li>Favorite artist? </li></ul></ul><ul><li>Opacity </li></ul><ul><ul><li>Me? </li></ul></ul><ul><ul><li>That gig? </li></ul></ul><ul><ul><li>A pizza? </li></ul></ul><ul><li>”Give me bands that I listened to in the month who are making a gig next to my current location” </li></ul>
  12. 12. The Google way <ul><li>Let's aggregate a massive amount of documents. By using the linkage information and statistical analysis, we can infer enough to provide a good search service. </li></ul>
  13. 13. Right, but... <ul><li>Search is not everything </li></ul><ul><ul><li>”Give me bands that I listened to in the last month who are making a gig next to my current location” </li></ul></ul><ul><li>Information extraction must cover: </li></ul><ul><ul><li>Multiple domains </li></ul></ul><ul><ul><li>Multiple media </li></ul></ul><ul><li>Frustrating </li></ul><ul><ul><li>Documents often generated from database </li></ul></ul><ul><ul><li>Why reverse-engineer the ”view” process? </li></ul></ul>
  14. 14. Silos and views
  15. 15. Solution <ul><li>Easy, let's just build web services on top of the WS-* stack, wrapping every single possible database query </li></ul>
  16. 16. <ul><li>Just jocking :-) </li></ul>
  17. 17. Web of data <ul><li>Let's get back to the Web: </li></ul><ul><ul><li>Names (URIs) </li></ul></ul><ul><ul><li>Documents (HTML, XML, JSON, ...) </li></ul></ul><ul><ul><li>Interactions (HTTP GET/POST/PUT/DELETE) </li></ul></ul><ul><li>Not only documents can be named !! </li></ul><ul><ul><li>Persons, cities, bands, WOD-PD... </li></ul></ul><ul><li>Documents can hold structured data </li></ul><ul><ul><li>Stuff that your program can use </li></ul></ul><ul><li>Problem solved. Session finished. </li></ul>
  18. 18. Web of data A web of things
  19. 19. RDF <ul><li>RDF is the web standard for such structured data </li></ul><ul><li>RDF data model: </li></ul><ul><ul><li>Subject (URI) </li></ul></ul><ul><ul><li>Property (URI) </li></ul></ul><ul><ul><li>Object (URI or literal) </li></ul></ul>
  20. 20. RDF literals <ul><li>Literals are just string values </li></ul><ul><li>They can have language tags associated with them </li></ul><ul><li>Or they can have a datatype associated with them </li></ul><ul><li>Or they can be plain </li></ul>
  21. 21. RDF example <ul><li>http://moustaki.org/foaf.rdf#moustaki </li></ul><ul><li>http://xmlns.com/foaf/0.1/based_near </li></ul><ul><li>http://dbpedia.org/resource/London </li></ul>
  22. 22. <ul><li>http://dbpedia.org/resource/The_Clash </li></ul><ul><li>http://dbpedia.org/property/origin </li></ul><ul><li>http://dbpedia.org/resource/London </li></ul>
  23. 23. <ul><li>http://moustaki.org/foaf.rdf#moustaki </li></ul><ul><li>http://xmlns.com/foaf/0.1/interest </li></ul><ul><li>http://dbpedia.org/resource/The_Clash </li></ul>
  24. 24. RDF Me The Clash London
  25. 25. The nice thing about all those URIs <ul><li>… is that you can look them up to get more information about the things they signify. </li></ul><ul><li>Even the properties and types are URIs. This means you can look them up to get more information about their semantics. </li></ul><ul><ul><li>Web ontologies </li></ul></ul><ul><li>You can also do handy things like retrieve the labels (rdfs:label) of the predicates, to create dynamic user interfaces. </li></ul>
  26. 26. Writing RDF <ul><li>RDF is the data model </li></ul><ul><li>Different ways to serialise RDF </li></ul><ul><ul><li>RDF/XML </li></ul></ul><ul><ul><li>Turtle </li></ul></ul><ul><ul><li>RDFa (RDF embedded in XHTML) </li></ul></ul>
  27. 27. RDF/XML <ul><li><foaf:Person rdf:about=” http://moustaki.org/foaf.rdf#moustaki ”> </li></ul><ul><li><foaf:knows rdf:resource=” http://sw-app.org/mic.xhtml#i ”/> </li></ul><ul><li><foaf:interest rdf:resource=” http://dbpedia.org/resource/The_Clash ”> </li></ul><ul><li><foaf:name>Yves Raimond</foaf:name> </li></ul><ul><li></foaf:Person> </li></ul>
  28. 28. Turtle <ul><li>< http://moustaki.org/foaf.rdf#moustaki > </li></ul><ul><li>a foaf:Person; </li></ul><ul><li>foaf:interest < http://dbpedia.org/resource/The_Clash >; </li></ul><ul><li>foaf:knows < http://sw-app.org/mic.xhtml#i >; </li></ul><ul><li>foaf:name ”Yves Raimond” . </li></ul>
  29. 29. Summary - Linked Data principles <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 RDF information </li></ul><ul><li>Include RDF statements that link to other URIs so that they can discover related things Tim Berners-Lee, 2007 http://www.w3.org/DesignIssues/LinkedData.html </li></ul>
  30. 30. Example <ul><li>http://dbtune.org/jamendo/artist/5 </li></ul><ul><li>RDF representation: </li></ul><ul><ul><li>This is an artist </li></ul></ul><ul><ul><ul><li>http://purl.org/ontology/mo/MusicArtist </li></ul></ul></ul><ul><ul><li>It made two records </li></ul></ul><ul><ul><ul><li>http://dbtune.org/jamendo/record/33 </li></ul></ul></ul><ul><ul><ul><li>http://dbtune.org/jamendo/record/174 </li></ul></ul></ul><ul><ul><li>It is based near a place </li></ul></ul><ul><ul><ul><li>http://sws.geonames.org/2991627/ </li></ul></ul></ul><ul><li>More information about that place? GET it! </li></ul>
  31. 31. Tabulator demo