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Linked Data

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My academic seminar presentation on Linked Data

My academic seminar presentation on Linked Data

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  • 1. Web == One huge DB A seminar on Linked Data and Semantic Web
  • 2. The Web of Linked Documents
  • 3. Issues of Linked Documents
    • Loosely structured Data
    • 4. Unstructured hyperlinks
    • 5. Disconnected Data
  • 6. What is Semantic Web? “ The first step is putting data on the Web in a form that machines can naturally understand, or converting it to that form. This creates what I call a Semantic Web – a web of data that can be processed directly or indirectly by machines.” ~ Tom Heath
  • 7. The Web of Linked Data
  • 8. The Semantic Web
    • This converts the whole web into a single database.
    • 9. Designed for machines and humans.
    • 10. Links between things-things and things-and its description.
    • 11. Encourages reuse, reduces redundancy
    • 12. Enables to add more value to data over the network.
  • 13. Linked Data Technology Stack
  • 17. URIs – Not Just for Web Pages
    • “A Uniform Resource Identifier (URI) provides a simple and extensible means for identifying a resource.” -- RFC 3986
    • 18. Examples
      • http://dbpedia.org/resource/Tim_Berners-Lee
      • 19. http://dbpedia.org/resource/Model_Engieering_College
      • 20. http://sws.geonames.org/4671654/
  • 21. HTTP
    • Data access mechanism
    • 22. Using http:// URIs to identify things allows people to look these things up
  • 23. RDF: Resource Description Framework
    • Data format for describing things and their interrelations.
    • 24. Descibes relations based on triples; subject-predicate-object
  • 25. The RDF Data Model
      subject -> predicate -> object Tom -> worksFor -> Talis Talis -> basedIn -> Birmingham <uri> -> <uri> -> <uri> eg: <http://dbpedia.org/resource/Talis_Group> <http://xmlns.com/foaf/0.1/based_near> <http://sws.geonames.org/3333125/>
  • 26. Data Merging with RDF
    • Consider a profile of Richard
  • 27. Data Merging with RDF
      This can be naturally merged
  • 28. Data Merging with RDF
    • This is linked Data
  • 29. Data discovery in RDF
  • 30. Advantages of RDF
    • Information in different sources merge naturally
    • 31. Clients can look up every URI in and RDF graph over the Web to get addictional info.
    • 32. Easy description of relations with the help of RDFS
  • 33. Linked Data principles
    • Use HTTP URIs
    • 34. Provide useful information in RDF
    • 35. Include RDF links to other URIs
  • 36. Why publish Linked Data?
    • Ease of discovery
    • 37. Ease of consumption
      • standards-based data sharing
    • Reduced redundancy
    • 38. Added value
      • build ecosystems around your data/content
  • 39. The Linking Open Data Project
  • 40. The Linking Open Data Project
    • Community project with W3C support
    • 41. Take existing open data sets
    • 42. Make them available on the Web in RDF
    • 43. Interlink them with other data sets
    • 44. Began early 2007
  • 45. LOD Cloud as on November 2007
  • 46. LOD Cloud as on March 2008
  • 47. LOD Cloud as on March 2009
  • 48. The latest LOD cloud as on July 2009
  • 49. Setting RDF links
    • RDF links enable LD browsers and crawlers to discover additional data
    • 50. The application domain determine the RDF properties used in predicate section.
      • eg: for describing people : foaf:knows, foaf:based_near
      • 51. for showing another same data source: owl:sameAs
    • We can set the RDF links manually and generate links automatically using algorithms.
  • 52. Generating RDF links manually
    • Identify the datasets you want to link to.
    • 53. Search for the right URIs to link to using search interfaces if provided. Or using LD browsers
    • 54. Use services like Uriqr to search for existing URIs and choose the most popular one suiting your need.
  • 55. Auto generating RDF links
    • Used on Large datasets
    • 56. Two major methods
      • Pattern Based algorithm
        • Searches the URIs on various data sets for similar patterns and link generate the RDF links
      • Property based algorithms
        • Searches additional informations of the resource at the resource end points rather than the URIs alone.
          • Eg: interlinking Dbpedia and Geonames.
  • 57. Now how to put it on Linked Data
    • Serve as static files
      • Simplest way is to produce static RDF files and upload them to your webserver.
        • When creating FOAF profiles, and RDF vocabularies
        • 58. RDF is generated by some other software.
    • Serving RDB on
      • The conventional DB is untouched
      • 59. A mapping is done to produce the RDF files.
      • 60. Tools like D2R server and OpenLink Virtuoso is used.
  • 61. RDB to Linked Data
  • 62. SPARQL
    • S PARQL P rotocol a nd R DF Q uery L anguage
    • 63. Retrieves data from RDF
    • 64. Similar to SQL syntax
      • Eg:
      • PREFIX foaf: < http://xmlns.org/foaf/0.1/ >
    SELECT ?acquaintance FROM < http://w3.org/People/Berners-Lee/card > WHERE { < http://w3.org/People/Berners-Lee/card#i > foaf:knows ?acquaintance . FILTER isURI(?acquaintance) }
  • 65. Linked Data Applications
  • 66. Linked Data Applications
    • Browsers
      • Marbles
    • Search engines
      • Falcons
    • Mashups
  • 69. Challanges
    • User Interface
    • 70. Link Maintenance
    • 71. Licensing
    • 72. Trust, Quality, Relevance
  • 73. Conclusions
    • Linked Data will enable revolution on how data will be used
    • 74. Machines will finally be able to search!!
    • 75. Researchers can have a wide range of related data to dig into.
  • 76. “ RAW DATA NOW! ” ~Tim Berners

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