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Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
Semantic Web introduction
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Semantic Web introduction

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Brief introduction into Semantic Web & Linked Data

Brief introduction into Semantic Web & Linked Data

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  • 1. IntroductionSemantic Web & Linked Data
  • 2. Resource Description Framework● W3C standard since 1999● Graph data model● Triples (graph elements) ● Subject: resource URI ● Property: resource URI ● Object: resource URI or literal value● Multiple syntaxes● Stored in triplestores● SPARQL query language
  • 3. Triples/QuadsGraph Subject Property Object http://www.w3.org/ http://www.w3.org/ http://www.w3.org/ People/EM/contact# 1999/02/22-rdf- 2000/10/swap/pim/c me syntax-ns#type ontact#Person http://www.w3.org/ http://www.w3.org/ "Eric Miller" People/EM/contact# 2000/10/swap/pim/c me ontact#fullName http://www.w3.org/ http://www.w3.org/ mailto:em@w3.org People/EM/contact# 2000/10/swap/pim/c me ontact#mailbox http://www.w3.org/ http://www.w3.org/ "Dr." People/EM/contact# 2000/10/swap/pim/c me ontact#personalTit leExample from RDF Primer
  • 4. RDF graph
  • 5. Multiple syntaxes● RDF/XML (the only W3C standard so far)● Plain text ● Turtle (soon W3C standard) ● N-Triples ● Notation3● Namespaces is a shorthand mechanism ● foo: http://example.org/somewhere/ ● ex: http://example.org/somewhere/ ● foo:bar = http://example.org/somewhere/bar ● foo:bar == ex:bar
  • 6. RDF/XML syntax<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"xmlns:contact="http://www.w3.org/2000/10/swap/pim/contact#"> <contact:Person rdf:about="http://www.w3.org/People/EM/contact#me"> <contact:fullName>Eric Miller</contact:fullName> <contact:mailbox rdf:resource="mailto:em@w3.org"/> <contact:personalTitle>Dr.</contact:personalTitle> </contact:Person></rdf:RDF>
  • 7. Turtle syntax@prefix contact: <http://www.w3.org/2000/10/swap/pim/contact#> .<http://www.w3.org/People/EM/contact#me> a contact:Person ; contact:fullName "Eric Miller" ; contact:mailbox <mailto:em@w3.org> ; contact:personalTitle "Dr." .
  • 8. OWL (Web Ontology Language)● Based on formal semantics ● Enables inference (reasoning)● Open world assumption ● Unknown is not false but undefined● Builds on RDF Schema ● Class (set of individuals) ● Property – Datatype – Object ● Instance (individual)
  • 9. Ontologies● Established, reusable vocabularies/schemas ● DublinCore: basic metadata ● FOAF: person and contact information ● SIOC: social media descriptions ● GoodRelations: e-commerce
  • 10. SPARQL: RDF query language● RDF graph pattern matching● The only standard NoSQL query language● SPARQL forms ● SPARQL Update forms ● SELECT ● INSERT DATA ● ASK ● DELETE DATA ● DESCRIBE ● INSERT/DELETE ● CONSTRUCT ● LOAD ● CLEAR
  • 11. SPARQL examplePREFIX contact: <http://www.w3.org/2000/10/swap/pim/contact#>SELECT *{ ?person contact:mailbox ?mbox } ?person ?mboxhttp://www.w3.org/People/EM/contact#me mailto:em@w3.org
  • 12. RDF & SPARQL tools● Frameworks ● Apache Jena ● Sesame● Triplestores ● Dydra (cloud) ● Stardog ● Virtuoso ● BigData
  • 13. Linked Data● Linked Data = RDF + REST● Linked Data platform (soon W3C standard) ● Item resources and container resources ● Implement HTTP methods ● Accept and return RDF descriptions● Uniform generic web API● The only global data integration approach
  • 14. Linked Data usage● Open datasources ● DBPedia ● Linked Life Data ● UK Open Data● In companies ● BBC: Semantic Publishing ● IBM: Linked Data Basic Profile 1.0
  • 15. Further reading● RDF Primer● OWL 2 Web Ontology Language Primer● SPARQL by Example● Learning SPARQL● Linked Data: Evolving the Web into a Global Data S
  • 16. Graphity● Generic open-source Linked Data platform ● Independent from domain models and datasources● Architecture ● Model: pure RDF, no object model (above RDF API) – Generated SPARQL queries load RDF from triplestore ● View – XSLT transforms RDF/XML to XHTML ● Controller – JAX-RS web application matches requests, queries & transforms
  • 17. Thanks. Questions?● Martynas Jusevičius● Vilnius/Copenhagen● martynas@graphity.org● @pumba_lt

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