Linked (Open) Data

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Guest Lecture about open data / linked data and the basics of linked open data held at the Technical University of Vienna

Text of Linked (Open) Data

  • 1.Linked (Open) Data VU Web Engineering / TU Wien May 27th 2013 - Bernhard Haslhofer -

2. About me Since 03/2013 Postdoc @ University of Vienna Previously Lecturer & Postdoc @ Cornell University, NY, USA Univ. Ass @ University of Vienna WINF TU Wien 2003, INF TU Wien 2006 2 3. About me Research Interests Web informaZon systems Globally connected, Web-based data networks Structured Web Data (Linked Data,, (FB) Open Graph Protocol, etc.) Knowledge Graphs (e.g., DBpedia, Freebase) AnnotaZons / SemanZc Tagging Quality in Open Data Networks . 3 4. My teaching philosophy A course is a collaboraZve experience Instructor provides Structure FoundaZon for learning Students Engage, contribute, challenge Ask quesZons! Think criZcally! Disagree if appropriate! 4Arent we beyond that? 5. My plan for today Linked (Open) Data ??? Linked Data Intro & Overview Linked Data - Technologies Recent Trends and Developments QuesZons / Discussion 5 6. Open Data Open data is data that can be freely used, reused and redistributed by anyone - subject only, at most, to the requirement to a:ribute and sharealike. (Open Data Handbook, 2012, Open Knowledge FoundaZon) 6 7. Open Data DeniZon Availability and Access Data must be available as a whole and at no more than a reasonable reproducZon cost, preferably by downloading over the internet Data must also be available in a convenient and modiable form Reuse and RedistribuZon Data must be provided under terms that permit reuse and redistribuZon including the intermixing with other datasets. Universal ParZcipaZon Everyone must be able to use, reuse and redistribute (no discriminaZon) No non-commercial restricZons (hip:// 7 8. Open Data Movement 8Source: 9. QuesZons Why should the open data principles sound familiar to sokware engineers? Any known open data examples? 9 10. Open Government Data Examples 10 11. Open Government Data Examples 11 12. Open Government Data Examples 12 13. Open Government Data Examples 13 14. Open Government Data Apps 14 15. Open (Government) Data Apps 15 16. Open Government Data in Journalism 16 17. (Open) Data Journalism 17 18. Open Data in Science 18 19. Open Data in Science 19 20. Linked Data A method of publishing structured data so that it can be interlinked and become more useful. It builds upon standard Web technologies such as HTTP, RDF and URIs, but rather than using them to serve web pages for human readers, it extends them to share informaLon in a way that can be read automaLcally by computers. This enables data from dierent sources to be connected and queried [Bizer, Heath, Berners-Lee 2009] 20 21. Linked Open Data 21Open Data + Linked Data = Linked Open Data 22. My plan for today Linked (Open) Data ??? Linked Data Intro & Overview Linked Data - Technologies Recent Trends and Developments QuesZons / Discussion 22 23. Linked Data context... 24. Why Linked Data? 25. Why Linked Data? 26. Why Linked Data? 27. Web Architecture 28. Web Architecture A set of simple standards Uniform global addressing (URI) Uniform document encoding (HTML) Uniform transportaZon (HTTP) Hyperlinks connecZng documents Works preiy well for accessing and exchanging documents 29. But someZmes we need to access the underlying structured data. 30. Web Services and Web APIs Source: 31. Web Services and Web APIs Each Web API has a proprietary interface Datasources must be known in advance InformaZon enZZes (papers, authors, subjects, etc.) are oken not linked 32. 32Social Networking Sites as Walled Gardens by David Simonds 33. Linked Data Vision Publish and link structured data on the Web Create a single globally connected data space based on the Web Architecture 34. Web of Linked Data A set of simple standards Uniform global addressing (URI) Uniform data model (RDF) Uniform transportaZon (HTTP) RDF links connecZng enZZes Forms a global data space and facilitates accessing and exchanging data 35. What is Linked Data? A method to build a Web of Data Architectural style, set of standards 36. Linking Open Data Project A W3C community project with the goal to extend the Web with a data commons by publishing various open data sets as RDF on the Web and by serng links between data items from dierent sources 37. ~$ curl -I -H "Accept: text/turtle"$ curl -H "Accept: text/turtle"$ sudo apt-get install raptor (Linux)~$ brew install raptor (Mac OSX)~$ rapper 38. My plan for today Linked (Open) Data ??? Linked Data Intro & Overview Linked Data - Technologies Recent Trends and Developments QuesZons / Discussion 50 39. Web / REST Basics - Recap Key Architectural Web Components IdenZcaZon: URI InteracZon: HTTP Standardized Document Formats: HTML, XML, JSON, etc. 51 40. Web / REST Basics - Recap URIs idenZfy interesZng things documents on the Web relevant aspects of a data set phone numbers, Skype usernames, e-mail addresses HTTP URIs name and address resources in Web-based systems 52 41. Web / REST Basics - Recap A resource can have several representaZons RepresentaZons can be in any format HTML XML JSON URIResourceRepresentationPlain Texttext/plain 42. Web / REST Basics - Recap We deal with resource representaZons not the resources themselves (pass by value) representaZons can be in any format (dened by media-type) Each resource implements a standard uniform interface (HTTP) a small set of verbs applied to a large set of nouns verbs are universal and not invented on a per-applicaZon basis Client ServerLogicalResourcesPhysicalResourcesJSONResource RepresentationsUniformInterface54 43. Web / REST Basics - Recap HTML, XHTML, ... XML, JSON, ... Transport and store dataDisplay information55 44. Web / REST Basics - Recap Example Web Service operaZons: Publish image on Flickr Order a book at Amazon Post a message on your friends Facebook wall Update user photo on foursquare WebApplication A Application BAPI56 45. RDF A data model for represenZng data on the Web Several statements (triples) form a graph Shining (lm)rdfs:label ()rdfs:label Jack Nicholsondbpedia-owl:birthDatefoaf:name 46. RDF/XML, N3, Turtle, etc. Data formats for RDF resource representaZons Used to transfer RDF data between apps 47. RDFS A language for describing the syntax and semanZcs of schemas/vocabularies in a machine-understandable way 48. OWL A more expressive (formal) language for dening the syntax and semanZcs of schemas/vocabularies Solves RDFS shortcomings but introduces quite some complexity 49. SKOS A language for describing controlled vocabularies (taxonomies, thesauri, classicaZon schemes) rdf:typeskos:broaderrdf:type 50. SPARQL A query language and protocol for accessing RDF data on the Web SELECT DISTINCT ?x!WHERE {!!?x dcterms:subject !! .!}! 51. Database Systems Analogy... Purpose Rela,onal Database Management Systems (RDBMS) Linked Data Technologies Query Schema DeniZon Language Data RepresentaZon IdenZers 63? 52. Database Systems Analogy... Purpose Rela,onal Database Management Systems (RDBMS) Linked Data Technologies Query SQL SPARQL Schema DeniZon Language SQL DDL RDFS / OWL Data RepresentaZon RelaZonal Model / Tables RDF / Graph IdenZers Primary Keys (numeric sequences) URI 64 53. Publishing Linked Data DisZnguish between non-informaZon and informaZon resource Sample non-informaZon resource hip:// Sample informaZon resource hip:// - HTML hip:// - RDF 54. Publishing Linked Data GET application/rdf+xml303 See OtherLocation: application/rdf+xml200 OK...!!!Bernhard Haslhofer,!!behas. !!

!! !301 College Avenue!! !Ithaca!! !United States!!

!! 60. 61. / Microdata example Pirates of the Carribean: On Stranger Tides (2011)!Jack Sparrow and Barbossa embark on a quest to find theelusive fountain!of youth, only to discover that Blackbeard and his daughterare after it too.!!Director: Rob Marshall!Writers: Ted Elliott, Terry Rossio, and 7 more credits!Stars: Johnny Depp, Penelope Cruz, Ian McShane!8/10 stars from 200 users. Reviews: 50.! 62. / Microdata example 63. Denes a number of types (e.g, person), organized in an inheritance hierarchy a number of properZes (e.g., name) Extension mechanisms to extend the schemas OWL representaZon: hip:// hip:// 76 64. Open Graph Protocol 65. 79 66. Google Knowledge Graph Enables search for things (people, places) that Google knows about Rooted in public sources such as Freebase, Wikipedia, CIA World Factbook, etc. augmented to 500M objects, 3.5B facts and relaZonship Next