Linked data and rdf
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This document provides an introduction to linked data and RDF. It discusses: 1. The principles of linked data, which involve using URIs to identify things and including links to other related resources. 2. The goals of linked data, which are to transfer information between machines without loss of meaning by identifying data on the web using shared vocabularies and RDF. 3. An overview of RDF, which structures data as subject-predicate-object triples and can be serialized in formats like RDF/XML and Turtle to represent typed links between resources.
![Principles
1. Use URIs to denote things.
2. Use HTTP URIs [#, /] so that these things can be
referred to and looked up ("dereferenced") by
people and user agents.
3. Provide useful information [metadata (aliases,
DC terms, technical: means of access, formats)]
about the thing when its URI is dereferenced,
leveraging standards such as RDF, SPARQL.
4. Include links to other [!] related things (using
their URIs) when publishing data on the Web
[reusing vocabularies].
http://en.wikipedia.org/wiki/Linked_data](https://image.slidesharecdn.com/linkeddataandrdf-131121034307-phpapp01/85/Linked-data-and-rdf-3-320.jpg)
![Concepts Things you should have heard about …
Data types
Expression of simple facts
Entailment
[Literals, URIrefs, RDF/XML, graphs]
http://www.w3.org/TR/rdf-concepts
Blank nodes](https://image.slidesharecdn.com/linkeddataandrdf-131121034307-phpapp01/85/Linked-data-and-rdf-12-320.jpg)
Linked data and rdf
- 1. Linked Data and RDF Semantic Engineering Seminar WS 2013/14 Daniel Nüst daniel.nuest@wwu.de
- 2. Linked Data WWW > Web of Documents CSV, XML, HTML tables >>> Web of Data Typed Links, to & from >>> global data graph LOD
- 3. Principles 1. Use URIs to denote things. 2. Use HTTP URIs [#, /] so that these things can be referred to and looked up ("dereferenced") by people and user agents. 3. Provide useful information [metadata (aliases, DC terms, technical: means of access, formats)] about the thing when its URI is dereferenced, leveraging standards such as RDF, SPARQL. 4. Include links to other [!] related things (using their URIs) when publishing data on the Web [reusing vocabularies]. http://en.wikipedia.org/wiki/Linked_data
- 4. 2.46 billion pieces of information (RDF triples) http://lod-cloud.net/ http://dbpedia.org/
- 7. RDF (.rdf) “HTML for data” the thing the value the property Goals/Applications transfer information between machines (not people) without loss of meaning, “identified on the web” Vocabularies (terms) for statements Serializations http://www.w3.org/TR/rdf-primer/ <Subject> <Predicate> <Object>
- 8. http://www.w3.org/TR/rdf-primer/ http://www.example.org/index.html has a creator whose value is John Smith
- 9. http://www.example.org/index.html has a creator whose value is John Smith http://www.w3.org/TR/rdf-primer/ http://www.example.org/index.html has a creation-date whose value is August 16, 1999 http://www.example.org/index.html has a language whose value is English
- 10. <http://www.example.org/index.html> <http://purl.org/dc/elements/1.1/creator> <http://www.example.org/staffid/8574 <http://www.example.org/index.html> <http://www.example.org/terms/creation-date> "August 16, 1999" . <http://www.example.org/index.html> <http://purl.org/dc/elements/1.1/language> "en" . (shared) Vocabularies namespace URI: http://www.example.org/ convention ex:index.html dc:creator exstaff:85740 . ex:index.html exterms:creation-date "August 16, 1999" . ex:index.html dc:language "en" . fy:joefy.iunm ed:dsfbups fytubgg:85740 . http://www.w3.org/TR/rdf-primer/ prefix ex: prefix dc: namespace URI: http://purl.org/dc/elements/1.1/ prefix exterms: namespace URI: http://www.example.org/terms/ prefix exstaff: namespace URI: http://www.example.org/staffid/
- 11. John Smith has a an age whose value is 27 <http://www.example.org/staffid/85740> <http://www.example.org/terms/age> "27"^^<http://www.w3.org/2001/XMLSchema#integer> . ex:index.html exterms:creation-date "1999-08-16"^^xsd:date . http://www.w3.org/TR/rdf-primer/ exstaff:85740 exterms:age "27"^^xsd:integer .
- 12. Concepts Things you should have heard about … Data types Expression of simple facts Entailment [Literals, URIrefs, RDF/XML, graphs] http://www.w3.org/TR/rdf-concepts Blank nodes
- 15. Turtle (.ttl) @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>. @prefix contact: <http://www.w3.org/2000/10/swap/pim/contact#>. <http://www.w3.org/People/EM/contact#me> rdf:type contact:Person; contact:fullName "Eric Miller"; contact:mailbox <mailto:em@w3.org>; contact:personalTitle "Dr.". http://www.w3.org/2007/02/turtle/primer/
- 17. <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" xmlns:geo="http://www.w3.org/2003/01/geo/wgs84_pos#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns="http://xmlns.com/foaf/0.1/"> <Person> <name>Dan Brickley</name> <homepage dc:title="Dan's home page" rdf:resource="http://danbri.org/"/> <based_near geo:lat="51.47026" geo:long="2.59466"/> <rdfs:seeAlso rdf:resource="http:/danbri.org/foaf.rdf"/> <!-- more RDF here, using any RDF vocabularies --> </Person> </rdf:RDF> http://www.w3.org/2003/01/geo/#example Geo, FOAF & DC
- 18. Resources and references > see handout! THANKS!
- 20. Linked data applications browsers – navigate/traverse data sources using links/RDF triples (connecting web of {documents, data}) search engines – start of the navigation human-oriented (like Google…) application-oriented (reuse indexing for different apps) domain applications Dbpedia Mobile, Revyu, DERI pipes, …
- 22. RDFs and OWL RDF Schema > http://en.wikipedia.org/wiki/RDF_Schema Web Ontology Language > http://en.wikipedia.org/wiki/Web_Ontology_Language more expressive See also https://www.cambridgesemantics.com/de/semantic-university/rdfs-vs.-owl