Introduction to Linked Data


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Presentation given at the "How to Consume Linked Data on the Web" Tutorial at 2009 International Semantic Web Conference

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Introduction to Linked Data

  1. 1. Introduction to Linked Data<br />Consuming Linked Data Tutorial<br />International Semantic Web Conference 2009<br />
  2. 2. Do you SEARCH or do you FIND?<br />
  3. 3. Search for<br />Football Players who went to the University of Texas at Austin, played for the Dallas Cowboys as Cornerback<br />
  4. 4.
  5. 5.
  6. 6.
  7. 7. Why can’t we just FIND it…<br />
  8. 8.
  9. 9.
  10. 10. Guess how I FOUND out?<br />
  11. 11. I’ll tell you how I did NOT find it<br />
  12. 12. Current Web = internet + links + docs<br />
  13. 13. So what is the problem?<br />The Web has problems<br />People aren’t interested in documents<br />They are interested in things <br />People can parse documents and extract meaning<br />Web pages are written in HTML<br />HTML describes visualization of information<br />Computers can’t!<br />
  14. 14. What do we need to do?<br />We need to help machines to understand the web so machines can help us understand things<br />They can learn what we are interested in<br />They can help us better find what we want<br />
  15. 15. How can we do that?<br />Besides publishing documents on the web<br />which computers can’t understand easily<br />Let’s publish something that computers can understand<br />
  16. 16. RAW DATA!<br />
  17. 17. But wait… don’t we do that already?<br />
  18. 18. Current Data on the Web<br />Relational Databases<br />APIs<br />XML<br />CSV<br />XLS<br />…<br />Can’t computers and applications already consume that data on the web?<br />
  19. 19. True! But it is all in different formats and data models!<br />
  20. 20. This makes it hard to integrate data<br />
  21. 21. The data in different data sources aren’t linked<br />
  22. 22. For example, how do I know that the Juan Sequeda in Facebook is the same as Juan Sequeda in Twitter<br />
  23. 23. Or if I create a mashup from different services, I have to learn different APIs and I get different formats of data back<br />
  24. 24. Wouldn’t it be great if we had a standard way of publishing data on the Web?<br />
  25. 25. We have a standardized way of publishing documents on the web, right?<br />HTML<br />
  26. 26. Then why can’t we have a standard way of publishing data on the Web?<br />
  27. 27. Good question! And the answer is YES. There is!<br />
  28. 28. Resource Description Framework (RDF)<br />A data model <br />A way to model data<br />i.e. Relational databases use relational data model<br />RDF is a triple data model<br />Labeled Graph<br />Subject, Predicate, Object<br />&lt;Juan&gt; &lt;was born in&gt; &lt;California&gt;<br />&lt;California&gt; &lt;is part of&gt; &lt;the USA&gt;<br />&lt;Juan&gt; &lt;likes&gt; &lt;the Semantic Web&gt;<br />
  29. 29. RDF can be serialized in different ways<br />RDF/XML<br />RDFa (RDF in HTML)<br />N3<br />Turtle<br />
  30. 30. So does that mean that I have to publish my data in RDF now?<br />
  31. 31. You don’t have to… but we would like you to <br />
  32. 32. An example<br />
  33. 33. Document on the Web<br />
  34. 34. Databases back up documents<br />THINGS have PROPERTIES:<br />A Book as a Title, an author, …<br />This is a THING:<br />A book title “Programming the Semantic Web” by Toby Segaran, …<br />
  35. 35. Lets represent the data in RDF<br />Programming the Semantic Web<br />title<br />author<br />book<br />Toby Segaran<br />isbn<br />978-0-596-15381-6<br />publisher<br />name<br />Publisher<br />O’Reilly<br />
  36. 36. Remember that we are on the web<br />Everything on the web is identified by a URI<br />
  37. 37. And now let’s link the data to other data<br />Programming the Semantic Web<br />title<br />author<br />http://…/isbn978<br />Toby Segaran<br />isbn<br />978-0-596-15381-6<br />publisher<br />name<br />http://…/publisher1<br />O’Reilly<br />
  38. 38. And now consider the data from<br />hasReview<br />http://…/review1<br />http://…/isbn978<br />description<br />reviewer<br />Awesome Book<br />http://…/reviewer<br />name<br />Juan Sequeda<br />
  39. 39. Let’s start to link data<br />hasReview<br />http://…/review1<br />http://…/isbn978<br />Programming the Semantic Web<br />title<br />description<br />sameAs<br />hasReviewer<br />Awesome Book<br />author<br />http://…/isbn978<br />Toby Segaran<br />http://…/reviewer<br />name<br />isbn<br />978-0-596-15381-6<br />Juan Sequeda<br />publisher<br />name<br />http://…/publisher1<br />O’Reilly<br />
  40. 40. Juan Sequeda publishes data too<br /><br /><br />livesIn<br />name<br />Juan Sequeda<br />
  41. 41. Let’s link more data<br />hasReview<br />http://…/review1<br />http://…/isbn978<br />description<br />hasReviewer<br />Awesome Book<br />http://…/reviewer<br />name<br />Juan Sequeda<br />sameAs<br /><br /><br />livesIn<br />name<br />Juan Sequeda<br />
  42. 42. And more<br />hasReview<br />http://…/review1<br />http://…/isbn978<br />Programming the Semantic Web<br />title<br />description<br />sameAs<br />hasReviewer<br />Awesome Book<br />author<br />http://…/isbn978<br />Toby Segaran<br />http://…/reviewer<br />name<br />isbn<br />978-0-596-15381-6<br />Juan Sequeda<br />publisher<br />sameAs<br />http://…/publisher1<br />name<br />O’Reilly<br /><br /><br />livesIn<br />name<br />Juan Sequeda<br />
  43. 43. Data on the Web that is in RDF andislinked to other RDF data is LINKED DATA<br />
  44. 44. Linked Data Principles<br />Use URIs as names for things<br />Use HTTP URIs so that people can look up (dereference) those names.<br />When someone looks up a URI, provide useful information.<br />Include links to other URIs so that they can discover more things.<br />
  45. 45. Linked Data makes the web appear as ONEGIANTHUGEGLOBALDATABASE!<br />
  46. 46. I can query a database with SQL. Is there a way to query Linked Data with a query language?<br />
  47. 47. Yes! There is actually a standardize language for that<br />SPARQL<br />
  48. 48. FIND all the reviews on the book “Programming the Semantic Web” by people who live in Austin<br />
  49. 49. hasReview<br />http://…/review1<br />http://…/isbn978<br />Programming the Semantic Web<br />title<br />description<br />sameAs<br />hasReviewer<br />Awesome Book<br />author<br />http://…/isbn978<br />Toby Segaran<br />http://…/reviewer<br />name<br />isbn<br />978-0-596-15381-6<br />Juan Sequeda<br />publisher<br />sameAs<br />name<br />http://…/publisher1<br />O’Reilly<br /><br /><br />livesIn<br />name<br />Juan Sequeda<br />
  50. 50. This looks cool, but let’s be realistic. What is the incentive to publish Linked Data?<br />
  51. 51. What was your incentive to publish an HTML page in 1990?<br />
  52. 52. 1) Share data in documents2) Because you neighbor was doing it<br />
  53. 53. So why should we publish Linked Data in 2009?<br />
  54. 54. 1) Share data as data2) Because you neighbor is doing it<br />
  55. 55. And guess who is starting to publish Linked Data now?<br />
  56. 56. Linked Data Publishers 2009<br />UK Government<br />US Government<br />BBC<br />Open Calais – Thomson Reuters<br />Freebase<br />NY Times<br />Best Buy<br />CNET<br />Dbpedia<br />Are you?<br />
  57. 57.
  58. 58. How can I publish Linked Data?<br />
  59. 59. Publishing Linked Data<br />Legacy Data in Relational Databases<br />D2R Server<br />Virtuoso<br />Triplify<br />Ultrawrap<br />CMS<br />Drupal<br />Native RDF Stores<br />Databases for RDF (Triple Stores)<br />AllegroGraph, Jena, Sesame, Virtuoso<br />Talis Platform (Linked Data in the Cloud)<br />In HTML with RDFa<br />
  60. 60. Questions?<br />