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Web of data
The document introduces the concept of the Web of Data, which builds upon linked data principles to publish structured data on the web using URIs, HTTP, and RDF. It describes how linked RDF data allows machines to understand web resources in a way that overcomes the shortcomings of untyped links by defining standardized semantics. Examples are given showing how RDF can represent relationships between resources and expose additional useful information by following the links between interconnected URIs.
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Web of data
- 1. Web of Data101 Keith Alexander (Talis) Yves Raimond (QMUL/BBC A&Mi) WOD-PD 2008, October 22 nd , 2008
- 2. Outline Introduction tolinked data 1 st hacking session SPARQL 2 nd hacking session What's out there?
- 3. The Web ofData
- 4. The Web Names(URIs) Documents (HTML, XML, JSON, ...) Interactions with names (HTTP) Names Documents HTTP GET
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- 6. What does itlook like, now? Names identify documents, e.g. HTML, XML, etc. Documents are interlinked: <a href=” http://moustaki.org/ ” />
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- 11. Shortcomings Untyped linksFriend? City? Favorite artist? Opacity Me? That gig? A pizza? ”Give me bands that I listened to in the month who are making a gig next to my current location”
- 12. The Google wayLet's aggregate a massive amount of documents. By using the linkage information and statistical analysis, we can infer enough to provide a good search service.
- 13. Right, but... Searchis not everything ”Give me bands that I listened to in the last month who are making a gig next to my current location” Information extraction must cover: Multiple domains Multiple media Frustrating Documents often generated from database Why reverse-engineer the ”view” process?
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- 15. Solution Easy, let'sjust build web services on top of the WS-* stack, wrapping every single possible database query
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- 17. Web of dataLet's get back to the Web: Names (URIs) Documents (HTML, XML, JSON, ...) Interactions (HTTP GET/POST/PUT/DELETE) Not only documents can be named !! Persons, cities, bands, WOD-PD... Documents can hold structured data Stuff that your program can use Problem solved. Session finished.
- 18. Web of dataA web of things
- 19. RDF RDF isthe web standard for such structured data RDF data model: Subject (URI) Property (URI) Object (URI or literal)
- 20. RDF literals Literalsare just string values They can have language tags associated with them Or they can have a datatype associated with them Or they can be plain
- 21. RDF example http://moustaki.org/foaf.rdf#moustakihttp://xmlns.com/foaf/0.1/based_near http://dbpedia.org/resource/London
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- 24. RDF Me TheClash London
- 25. The nice thingabout all those URIs … is that you can look them up to get more information about the things they signify. Even the properties and types are URIs. This means you can look them up to get more information about their semantics. Web ontologies You can also do handy things like retrieve the labels (rdfs:label) of the predicates, to create dynamic user interfaces.
- 26. Writing RDF RDFis the data model Different ways to serialise RDF RDF/XML Turtle RDFa (RDF embedded in XHTML)
- 27. RDF/XML <foaf:Person rdf:about=”http://moustaki.org/foaf.rdf#moustaki ”> <foaf:knows rdf:resource=” http://sw-app.org/mic.xhtml#i ”/> <foaf:interest rdf:resource=” http://dbpedia.org/resource/The_Clash ”> <foaf:name>Yves Raimond</foaf:name> </foaf:Person>
- 28. Turtle < http://moustaki.org/foaf.rdf#moustaki> a foaf:Person; foaf:interest < http://dbpedia.org/resource/The_Clash >; foaf:knows < http://sw-app.org/mic.xhtml#i >; foaf:name ”Yves Raimond” .
- 29. Summary - LinkedData principles Use URIs as names for things Use HTTP URIs so that people can look up those names When someone looks up a URI, provide useful RDF information Include RDF statements that link to other URIs so that they can discover related things Tim Berners-Lee, 2007 http://www.w3.org/DesignIssues/LinkedData.html
- 30. Example http://dbtune.org/jamendo/artist/5 RDFrepresentation: This is an artist http://purl.org/ontology/mo/MusicArtist It made two records http://dbtune.org/jamendo/record/33 http://dbtune.org/jamendo/record/174 It is based near a place http://sws.geonames.org/2991627/ More information about that place? GET it!
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