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/Quads
Graph 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
le
Example from RDF Primer
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
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