This document discusses the evolution of the web from a web of documents to a web of linked data. It outlines the principles of linked data, which involve using URIs to identify things and linking those URIs to other URIs so that machines can discover more data. RDF is introduced as a standard data model for publishing linked data on the web using triples. Examples of linked data applications and datasets are provided to illustrate how linked data allows the web to function as a global database.

1. Β´μέρος: linked dataAfter XML: semantic WebMostly for research and sophisticated businessLightweight Semantic Web = Linked Data 1

2. From Al Gore (internet highways) to Barack Obama (linked data)2

3. The Web of DocumentsAnalogy:a global file system

4. Designed for: human consumption

5. Primary objects: documents

6. Links between: documents(or sub-parts of)

7. Degree of structure in objects: fairly low

8. Semantics of content and links: implicit (humans)(Tom Heath)The web = the internet+ links + documents3

9. The Web of DocumentsSimple, big and unstructured

10. Organized in SilosBut humans are interested in:Things, no documents and

11. these Thingsmight bein documents or elsewhereHumans: Limited capacity to extract meaning...4

12. Limited SEARCH capacitySearch for: Football Players who went to the University of Texas at Austin, played for the Dallas Cowboys as Cornerback(Juan F. Sequeda)5

13. Google, Bing, yahoo! irrelevant6

14. Wikipedia through LD: relevant7

15. The Web of DataAnalogy:a global filesystem----> globaldatabase

16. Designed for: human consumption ->machines first, humans later

17. Primary objects: documents --> things (or descriptions of things)

18. Links between: documents--> things

19. Degree of structure in objects: fairly low ---> high

20. Semantics of content and links: implicit --> explicit(Tom Heath)8

21. The Modigliani TestShow me all the locations of all the original paintings of ModiglianiDaniel Koller (@dakoller) showed that you can find this with a SPARQL query on DBpediaThanks Richard MacManus - ReadWriteWeb

23. Results of the Modigliani TestAtanas Kiryakov from OntotextUsed LDSR – Linked Data Semantic RepositoryDbpediaFreebaseGeonamesUMBELWordnetPublished April 26, 2010: http://www.readwriteweb.com/archives/the_modigliani_test_for_linked_data.php

25. The Web of Data: why?– encourages reuse– reduces redundancy– maximises its (real and potential) inter-connectedness– enables network effects to add value to data13

26. The Web of Data: how?– current state on the WebRelational Databases

27. APIs

28. XML

29. CSV

30. XLS(see EXHIBIT)Computers can’t consume data because:Different formats & models

31. Not inter-connected14

32. The Web of Data: how?– we need to create a standard way of publishing Data on the Web (like HTML for docs)This is the Resource Description Framework (RDF)(a simple example here from Juan F. Sequeda), more next semester!)15

33. Resource Description Framework (RDF)A data model

34. A way to model data

35. Inspired form Relational databases and Logic

36. RDF is a triple data model

37. Labeled Graph (semantic networks)

38. Subject, Predicate, Object<Isidoro> <was born in> <Chios><Chios> <is part of> <Greece>

39. The RDF Data ModelTriplessubject -> predicate -> objectTom -> worksFor -> TalisTalis -> basedIn -> Birmingham<uri> -> <uri> -> <uri> or "literal"

40. παράδειγμα“Talis is Based Near Birmingham”<http://dbpedia.org/resource/Talis_Group><http://xmlns.com/foaf/0.1/based_near><http://sws.geonames.org/3333125/>

42. Example: Document on the Web

43. Databases back up documentsTHINGS have PROPERTIES:A Book as a Title, an author, …This is a THING:A book title “Programming the Semantic Web” by Toby Segaran, …

44. Data representation in RDFProgramming the Semantic WebtitleauthorbookToby Segaranisbn978-0-596-15381-6publishernamePublisherO’Reilly

45. Everything on the web is identified by a URI!

46. link the data to other dataProgramming the Semantic Webtitleauthorhttp://…/isbn978Toby Segaranisbn978-0-596-15381-6publishernamehttp://…/publisher1O’Reilly

47. consider the data from Revyu.comhasReviewhttp://…/review1http://…/isbn978descriptionreviewerAwesome Bookhttp://…/reviewernameJuan Sequeda

48. start to link datahasReviewhttp://…/review1http://…/isbn978Programming the Semantic WebtitledescriptionsameAshasReviewerAwesome Bookauthorhttp://…/isbn978Toby Segaranhttp://…/reviewernameisbn978-0-596-15381-6Juan Sequedapublishernamehttp://…/publisher1O’Reilly

49. Juan Sequeda publishes data toohttp://juansequeda.com/idhttp://dbpedia.org/AustinlivesInnameJuan Sequeda

50. Let’s link more datahasReviewhttp://…/review1http://…/isbn978descriptionhasReviewerAwesome Bookhttp://…/reviewernameJuan SequedasameAshttp://juansequeda.com/idhttp://dbpedia.org/AustinlivesInnameJuan Sequeda

51. And morehasReviewhttp://…/review1http://…/isbn978Programming the Semantic WebtitledescriptionsameAshasReviewerAwesome Bookauthorhttp://…/isbn978Toby Segaranhttp://…/reviewernameisbn978-0-596-15381-6Juan SequedapublishersameAshttp://…/publisher1nameO’Reillyhttp://juansequeda.com/idhttp://dbpedia.org/AustinlivesInnameJuan Sequeda

52. Linked data = internet + http + RDF

53. Linked Data PrinciplesUse URIs as names for thingsUse URIs so that people can look up (dereference) those names.When someone looks up a URI, provide useful information.Include links to other URIs so that they can discover more things.

54. Web as a databaseLinked Data makes the web exploitable as ONE GIANT HUGE GLOBAL DATABASE!Is there any query language like sql?SPARQL… (next semester)

55. History of LDLinked Data Design Issues by TimBL July 2006

56. Linked Open Data Project WWW2007

57. First LOD Cloud May 2007

58. 1st Linked Data on the Web Workshop WWW2008

59. 1stTriplification Challenge 2008

60. How to Publish Linked Data Tutorial ISWC2008

61. BBC publishes Linked Data 2008

62. 2nd Linked Data on the Web Workshop WWW2009

63. NY Times announcement SemTech2009 - ISWC09

64. 1st Linked Data-a-thon ISWC2009

65. 1st How to Consume Linked Data Tutorial ISWC2009

66. Data.gov.uk publishes Linked Data 2010

67. 2st How to Consume Linked Data Tutorial WWW2010

68. 1st International Workshop on Consuming Linked Data COLD2010

69. El.dbpedia.orgMay 2007

71. What is a Linked Data application/service?Software system that makes use of data on the Web from multiple datasets and that benefits from links between the datasets

72. Characteristics of Linked Data ApplicationsConsume 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. Discover further information by following the links between different data sources: the fourth principle enables this.

74. Combine the consumed linked data with data from sources (not necessarily Linked Data)

75. Expose the combined data back to the web following the Linked Data principles

76. Offer value to end-usersthe 5 stars of open linked data★make your stuff available on the Web (whatever format)★★make it available as structured data (e.g. excel instead of image scan of a table)★★★non-proprietary format (e.g. csv instead of excel)★★★★use URLs to identify things, so that people can point at your stuff★★★★★link your data to other people’s data to provide contexthttp://lab.linkeddata.deri.ie/2010/star-scheme-by-example/

77. Examples Data.gov.uk

78. http://wheredoesmymoneygo.org/

79. http://energy.publicdata.eu/ee/vis.html

80. Greece – not in Linked Data!

81. http://geodata.gov.gr/geodata/

82. Fuelprices.gr

83. E-prices.gr

84. Et.diavgeia.gov.gr40

85. 41

86. More Exampleshttp://data-gov.tw.rpi.edu/wikihttp://dbrec.net/http://fanhu.bz/http://data.nytimes.com/schools/schools.htmlhttp://sig.mahttp://visinav.deri.org/semtech2010/