Introduction to Linked Data 1/5


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Introduction to Linked Data 1/5

  1. 1. Introduction to Linked Data<br />Juan F. Sequeda<br />Semantic Technology Conference<br />June 2011<br />
  2. 2. What is the Semantic Web?<br />
  3. 3. What is the Semantic Web?<br />
  4. 4. Internet != Web<br />
  5. 5.
  6. 6. What is the Web?<br />“… the Web, is a system of interlinked hypertext documents accessed via the Internet. With a web browser, one can view web pages that may contain text, images […] and navigate between them via hyperlinks”<br /><br />
  7. 7. Current Web = internet + links + docs<br />
  8. 8. History of the Web<br />Created by Tim Berners-Lee at CERN in 1989<br />Mosaic browser in 1993<br />W3C created in 1994<br />Exponential growth mid 90s<br />Amazon, Ebay – 1995<br />Search engines – Google 1998<br />Dot-com boom 1997 – 2001<br />Web 2.0 – blogs, Facebook, Twitter, etc<br />
  9. 9. What is the problem?<br />
  11. 11.
  12. 12.
  13. 13.
  14. 14. What is the problem?<br />The web is full of documents<br />We aren’t always interested in documents<br />We are interested in THINGS<br />These THINGS might be in documents<br />We can read a HTML document rendered in a browser and find what we are searching for<br />This is hard for computers. <br />Computers have to guess (even though they are pretty good at it)<br />
  15. 15. The Web is a Data Shredder<br />Structured Data<br />Unstructured Data<br />Thanks Martin Hepp<br />
  16. 16. What would we like?<br />Make it easy for computers/software to find THINGS<br />Do you SEARCH or do you FIND?<br />
  17. 17. Search for<br />Football Players who went to the University of Texas at Austin, played for the Dallas Cowboys as Cornerback<br />
  18. 18.
  19. 19.
  20. 20.
  21. 21. Why can’t we just FIND it…<br />
  22. 22.
  23. 23.
  24. 24. Guess how I FOUND out?<br />
  25. 25. On a Semantic Web<br />Besides publishing documents on the web<br />which computers can’t understand easily<br />Let’s publish on the web something that computers can understand<br />DATA<br />
  26. 26. The Semantic Web is a web of linked data<br />The current web is a web of <br />linked documents<br />
  27. 27. But wait… doesn’t the web already have data?<br />
  28. 28. 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 />
  29. 29. Yes! But it is all in different formats and data models!<br />
  30. 30. This makes it hard to integrate data<br />
  31. 31. The data in different data sources aren’t linked<br />
  32. 32. For example, how do I know that the Juan Sequeda in Facebook is the same as Juan Sequeda in Twitter<br />
  33. 33. Or if I create a mashup from different services, I have to learn different APIs and I get different formats of data back<br />
  34. 34. Data is Siloed<br />
  35. 35. Wouldn’t it be great if we had a standard way of publishing data on the Web?<br />
  36. 36. We have a standardized way of publishing documents on the web, right?<br />HTML<br />
  37. 37. Then why can’t we have a standard way of publishing data on the Web?<br />
  38. 38. Good question! And the answer is YES. There is!<br />RDF<br />
  39. 39. 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 /><Juan> <was born in> <California><br /><California> <is part of> <the USA><br /><Juan> <has hobby> <Salsa dancing><br />
  40. 40. RDF can be serialized in different ways<br />RDF/XML<br />RDFa (RDF in HTML)<br />N3<br />Turtle<br />JSON<br />
  41. 41. So does that mean that I have to publish my data in RDF now?<br />
  42. 42. You don’t have to… but we would like you to <br />
  43. 43. An example<br />
  44. 44. Document on the Web<br />
  45. 45. 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 />
  46. 46. 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 />
  47. 47. Remember that we are on the web<br />Everything on the web is identified by a URI<br />
  48. 48. 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 />
  49. 49. 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 />
  50. 50. 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 />
  51. 51. Juan Sequeda publishes data too<br /><br /><br />livesIn<br />name<br />Juan Sequeda<br />
  52. 52. 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 />
  53. 53. 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 />
  54. 54. Data on the Web that is in RDF and is linked to other RDF data is LINKED DATA<br />
  55. 55. 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 />
  56. 56. Linked Data makes the web appear as ONEGIANTHUGEGLOBALDATABASE!<br />
  57. 57. I can query a database with SQL. Is there a way to query Linked Data with a query language?<br />
  58. 58. Yes! There is actually a standardize language for that<br />SPARQL<br />
  59. 59. FIND all the reviews on the book “Programming the Semantic Web” by people who live in Austin<br />
  60. 60. SELECT ?review ?comment<br />WHERE {<br /> isbn:978 ex:hasReview ?review .<br /> ?review ex:description ?comment .<br /> ?review ex:hasReviewer ?person .<br /> ?person ex:livesdbpedia:Austin .<br />} <br />
  61. 61. SELECT ?review ?comment<br />WHERE {<br />isbn:978 ex:hasReview ?review .<br />?review ex:description ?comment .<br />?review ex:hasReviewer ?person .<br />?person ex:livesdbpedia:Austin .<br />}<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 />name<br />http://…/publisher1<br />O’Reilly<br /><br /><br />livesIn<br />name<br />Juan Sequeda<br />
  62. 62. This looks cool, but let’s be realistic. What is the incentive to publish Linked Data?<br />
  63. 63. What was your incentive to publish an HTML page in 1990?<br />
  64. 64. 1) Share data in documents2) Because you neighbor was doing it… later on …3) Marketing, Advertising, SEO<br />
  65. 65. So why should we publish Linked Data in 2011?<br />
  66. 66. 1) Share data as data2) Because you neighbor is doing it…3) (Semantic) SEO ++<br />
  67. 67. Linked Data Publishers<br />UK Government<br />US Government<br />BBC<br />Open Calais – Thomson Reuters<br />Freebase/Google<br />NY Times<br />Best Buy<br />CNET<br />Dbpedia<br /><br />O’Reilly Media<br />…<br />
  68. 68. May 2007<br />
  69. 69. Oct 2007<br />
  70. 70. Nov 2007<br />
  71. 71. Feb 2008<br />
  72. 72. Mar 2008<br />
  73. 73. Sept 2008<br />
  74. 74. Mar 2009 (1)<br />
  75. 75. Mar 2009 (2)<br />
  76. 76. July 2009<br />
  77. 77. September 2010<br />
  78. 78. June 2011<br />YOU GET THE PICTURE<br />ITS BIG and getting BIGGER and<br />BIGGER<br />
  79. 79. QUESTIONS?<br />