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Hacking with Semantic Web


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Hacking with Semantic Web

  1. 1. Hacking with Semantic Web Tom Praison Developer @ Yahoo!
  2. 2. What’s in here?• Evolution of the web• Poorly Solved Information Needs• Semantic Web Technologies• Linked Data• Demo of, a site built using open datasets• Some techniques for getting Structured Information from Web.• Demo of Yahoo! Contextual Analysis Platform and Open Dapper
  3. 3. I just had to take the hypertext idea and connect it to the Transmission Control Protocol and domain name system ideas and—ta-da!—the World Wide Web.Tim Berners Lee – Inventor of the WWW
  4. 4. WEB 1.0Few Content Creators! Majority Consumers!
  5. 5. WEB 2.0 Web as a platform
  6. 6. WEB 1.0 vs WEB 2.0 Ofoto Flickr Personal Website Blogging Britannica Online WikipediaDirectories(taxonomy) Tagging(“folksonomy”)Content Management Wikis Systems
  7. 7. WEB 3.0 Which direction will it take?
  8. 8. Semantic WebVirtual Web WEB 3.0 Pervasive Web Could be anything! Artificial Personalization Intelligence
  9. 9. Today’s WebA Web of Documents rather than Data!
  10. 10. Poorly Solved Information Needs• Multiple interpretations – Apple• Long tail queries – Roja (I meant a south indian actress)• Imprecise or overly precise searches – jim hendler – pictures of strong adventures people• Searches for descriptions – countries in africa – 25 year old computer engineer living in Bangalore – Reliable smart phone under 15,000 rupees
  11. 11. THE SOLUTION Semantic Web
  12. 12. Publish data on the Web• Linked Data: linking data similar to how we link documents on the Web• Query databases over the Web
  13. 13. Architectural Challenges• A common format for sharing data• Sharing the meaning of data• Infrastructure
  14. 14. Semantic Web standards from W3C• Data and schema languages (RDF, OWL, RIF)• Document formats (RDF/XML, RDFa)• Protocols (SPARQL, HTTP)
  15. 15. Current Researches & Other Efforts• Semantic Web research into knowledge representation and reasoning, data integration, data quality and many other topics• Community effort (Linked Data movement)
  16. 16. RDF (Resource Description Framework)• The basic data model of the Semantic Web – A universal model to capture all sorts of data: networks, relational, object-oriented…• Basic unit of information is a triple – A tuple of (subject, predicate, object) – Example: (Joe, loves, Mary) – Each triple gives the value of a property for a given resource or relates two objects to one another • Object is either a resource or a literal• An RDF model is a set of triples – Ordering of statements in an RDF document is irrelevant (unlike XML)
  17. 17. Graphical and textual notation foaf:Person type my:Joe name “Joe A.”A number of ways to serialize an RDF model into an RDF document RDF/XML, Turtle, N3, N-Triples
  18. 18. RDF is designed for the Web• URIs provide web-wide global identification across datasets – A resource may be described by multiple documents – URIs are intended to be reused – Unique, but not single identifiers: two URIs may denote the same thing
  19. 19. RDF is designed for the Web• URIs can be retrieved from the Web – A well-behaved URI returns a description of the resource – Provides authority: the definition of foaf:Person lives at that URI• Ontologies can be looked up as well – Typically at the root of the URIs, also known as the namespace – Example: redirects to the specification
  20. 20. URIs implicitly link data together (#joe, #loves, #mary)(#joe, #name, “Joe A.”)(#joe, #email, A social networking site (#mary, name, “Mary B.”) Joe’s homepage (#mary, gender, “female”) Mary’s homepage (#name, #type, #Property) (#name, #domain, #Person) Schema doc
  21. 21. Put together, triples form a single ‘global’ graph #name “Joe A.”#joe #email “” #loves #name “Mary B.” #mary #gender “female”
  22. 22. RDF Example
  23. 23. Linked Data cloud: interlinked RDF datasets on the Web
  24. 24. DBPedia• Dbpedia is dataset that contains much of the structured data in Wikipedia – Data from the info-boxes – Links between Wikipedia pages – Categories – Disambiguation and redirect pages• Links to other datasets
  25. 25. Fetching individual resources• Use your web browser • redirects to • You can plug in this URI into other Linked Data browsers• HTTP GET to fetch data – Using curl: add Accept: application/rdf+xml for RDF and enable redirect • curl -L -H Accept:application/rdf+xml’• Data dumps –
  26. 26. Querying using SPARQL• Interactive query builders • SPARQL Explorer: • Examples at:• Using HTTP GET – GET /sparql/?query=EncodedQuery HTTP/1.1 – Example: • SELECT ?film ?x WHERE { ?film <> <> . ?film <> <>} • curl’
  27. 27.• Award winning app in WWW2012 Metadata Challenge.• is a desktop / mobile HTML5 based application designed for conference attendees.• Built with the help of open datasets from and various other sources.
  28. 28. Some Techniques for getting Structured Information from Web• Semantic Markup• NER• Extraction Tools (Dapper)
  29. 29. Semantic Markup• Microdata (• RDFa• Open Graph Protocol (• Example: =
  30. 30. NER – Named Entity Recognition• Yahoo! Content Analysis API•
  31. 31. Dapperhttp://open.dapper.netDapper is a tool that enables users to create update feeds fortheir favorite sites and website owners to optimize anddistribute their content in new ways.
  32. 32. References•• 5-stars-of-open-linked-data/••