2011 05-01 linked data

908 views

Published on

Published in: Education
  • Be the first to comment

  • Be the first to like this

2011 05-01 linked data

  1. 1. Β´μέρος: linked data<br />After XML: semantic Web<br />Mostly for research and sophisticated business<br />Lightweight Semantic Web = Linked Data <br />1<br />
  2. 2. From Al Gore <br />(internet highways) <br />to Barack Obama <br />(linked data)<br />2<br />
  3. 3. The Web of Documents<br /><ul><li>Analogy:a global file system
  4. 4. Designed for: human consumption
  5. 5. Primary objects: documents
  6. 6. Links between: documents(or sub-parts of)
  7. 7. Degree of structure in objects: fairly low
  8. 8. Semantics of content and links: implicit (humans)</li></ul>(Tom Heath)<br />The web = the internet<br />+ links + documents<br />3<br />
  9. 9. The Web of Documents<br /><ul><li>Simple, big and unstructured
  10. 10. Organized in Silos</li></ul>But humans are interested in:<br /><ul><li>Things, no documents and
  11. 11. these Thingsmight be</li></ul>in documents or elsewhere<br /><ul><li>Humans: Limited capacity </li></ul>to extract meaning...<br />4<br />
  12. 12. Limited SEARCH capacity<br />Search for: Football Players who went to the University of Texas at Austin, played for the Dallas Cowboys as Cornerback<br />(Juan F. Sequeda)<br />5<br />
  13. 13. Google, Bing, yahoo! irrelevant<br />6<br />
  14. 14. Wikipedia through LD: relevant<br />7<br />
  15. 15. The Web of Data<br /><ul><li>Analogy:a global filesystem----> globaldatabase
  16. 16. Designed for: human consumption ->machines first, humans later
  17. 17. Primary objects: documents --> things (or descriptions of things)
  18. 18. Links between: documents--> things
  19. 19. Degree of structure in objects: fairly low ---> high
  20. 20. Semantics of content and links: implicit --> explicit</li></ul>(Tom Heath)<br />8<br />
  21. 21. The Modigliani Test<br />Show me all the locations of all the original paintings of Modigliani<br />Daniel Koller (@dakoller) showed that you can find this with a SPARQL query on DBpedia<br />Thanks Richard MacManus - ReadWriteWeb<br />
  22. 22.
  23. 23. Results of the Modigliani Test<br />Atanas Kiryakov from Ontotext<br />Used LDSR – Linked Data Semantic Repository<br />Dbpedia<br />Freebase<br />Geonames<br />UMBEL<br />Wordnet<br />Published April 26, 2010:<br /> http://www.readwriteweb.com/archives/the_modigliani_test_for_linked_data.php<br />
  24. 24.
  25. 25. The Web of Data: why?<br />– encourages reuse<br />– reduces redundancy<br />– maximises its (real and potential) inter-connectedness<br />– enables network effects to add value to data<br />13<br />
  26. 26. The Web of Data: how?<br />– current state on the Web<br /><ul><li>Relational Databases
  27. 27. APIs
  28. 28. XML
  29. 29. CSV
  30. 30. XLS</li></ul>(see EXHIBIT)<br />Computers can’t consume data because:<br /><ul><li>Different formats & models
  31. 31. Not inter-connected</li></ul>14<br />
  32. 32. The Web of Data: how?<br />– we need to create a standard way of publishing Data on the Web (like HTML for docs)<br />This is the Resource Description Framework (RDF)<br />(a simple example here from Juan F. Sequeda), more next semester!)<br />15<br />
  33. 33. Resource Description Framework (RDF)<br /><ul><li>A data model
  34. 34. A way to model data
  35. 35. Inspired form Relational databases and Logic
  36. 36. RDF is a triple data model
  37. 37. Labeled Graph (semantic networks)
  38. 38. Subject, Predicate, Object</li></ul><Isidoro> <was born in> <Chios><br /><Chios> <is part of> <Greece><br />
  39. 39. The RDF Data Model<br />Triples<br />subject -> predicate -> object<br />Tom -> worksFor -> Talis<br />Talis -> basedIn -> Birmingham<br /><uri> -> <uri> -> <uri> or "literal"<br />
  40. 40. παράδειγμα<br />“Talis is Based Near Birmingham”<br /><http://dbpedia.org/resource/Talis_Group><br /><http://xmlns.com/foaf/0.1/based_near><br /><http://sws.geonames.org/3333125/><br />
  41. 41.
  42. 42. Example: Document on the Web<br />
  43. 43. 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 />
  44. 44. Data representation 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 />
  45. 45. Everything on the web is identified by a URI!<br />
  46. 46. 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 />
  47. 47. consider the data from Revyu.com<br />hasReview<br />http://…/review1<br />http://…/isbn978<br />description<br />reviewer<br />Awesome Book<br />http://…/reviewer<br />name<br />Juan Sequeda<br />
  48. 48. 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 />
  49. 49. Juan Sequeda publishes data too<br />http://juansequeda.com/id<br />http://dbpedia.org/Austin<br />livesIn<br />name<br />Juan Sequeda<br />
  50. 50. 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 />http://juansequeda.com/id<br />http://dbpedia.org/Austin<br />livesIn<br />name<br />Juan Sequeda<br />
  51. 51. 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 />http://juansequeda.com/id<br />http://dbpedia.org/Austin<br />livesIn<br />name<br />Juan Sequeda<br />
  52. 52. Linked data = internet + http + RDF<br />
  53. 53. Linked Data Principles<br />Use URIs as names for things<br />Use 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 />
  54. 54. Web as a database<br />Linked Data makes the web exploitable as ONE GIANT HUGE GLOBAL DATABASE!Is there any query language like sql?SPARQL… (next semester)<br />
  55. 55. History of LD<br /><ul><li>Linked Data Design Issues by TimBL July 2006
  56. 56. Linked Open Data Project WWW2007
  57. 57. First LOD Cloud May 2007
  58. 58. 1st Linked Data on the Web Workshop WWW2008
  59. 59. 1stTriplification Challenge 2008
  60. 60. How to Publish Linked Data Tutorial ISWC2008
  61. 61. BBC publishes Linked Data 2008
  62. 62. 2nd Linked Data on the Web Workshop WWW2009
  63. 63. NY Times announcement SemTech2009 - ISWC09
  64. 64. 1st Linked Data-a-thon ISWC2009
  65. 65. 1st How to Consume Linked Data Tutorial ISWC2009
  66. 66. Data.gov.uk publishes Linked Data 2010
  67. 67. 2st How to Consume Linked Data Tutorial WWW2010
  68. 68. 1st International Workshop on Consuming Linked Data COLD2010
  69. 69. El.dbpedia.org</li></li></ul><li>May 2007<br />
  70. 70.
  71. 71. What is a Linked Data application/service?<br />Software system that makes use of data on the Web from multiple datasets and that benefits from links between the datasets<br />
  72. 72. Characteristics of Linked Data Applications<br /><ul><li>Consume data that is published on the web following the Linked Data principles: an application should be able to request, retrieve and process the accessed data
  73. 73. Discover further information by following the links between different data sources: the fourth principle enables this.
  74. 74. Combine the consumed linked data with data from sources (not necessarily Linked Data)
  75. 75. Expose the combined data back to the web following the Linked Data principles
  76. 76. Offer value to end-users</li></li></ul><li>the 5 stars of open linked data<br />★make your stuff available on the Web (whatever format)<br />★★make it available as structured data (e.g. excel instead of image scan of a table)<br />★★★non-proprietary format (e.g. csv instead of excel)<br />★★★★use URLs to identify things, so that people can point at your stuff<br />★★★★★link your data to other people’s data to provide context<br />http://lab.linkeddata.deri.ie/2010/star-scheme-by-example/<br />
  77. 77. Examples <br /><ul><li>Data.gov.uk
  78. 78. http://wheredoesmymoneygo.org/
  79. 79. http://energy.publicdata.eu/ee/vis.html
  80. 80. Greece – not in Linked Data!
  81. 81. http://geodata.gov.gr/geodata/
  82. 82. Fuelprices.gr
  83. 83. E-prices.gr
  84. 84. Et.diavgeia.gov.gr</li></li></ul><li>40<br />
  85. 85. 41<br />
  86. 86. More Examples<br />http://data-gov.tw.rpi.edu/wiki<br />http://dbrec.net/<br />http://fanhu.bz/<br />http://data.nytimes.com/schools/schools.html<br />http://sig.ma<br />http://visinav.deri.org/semtech2010/<br />

×