Sesam4   project presentation sparql - april 2011
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Sesam4 project presentation sparql - april 2011

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This slide set is a provided by the SESAM4 consortium as one out of three Technology Primers on Semantic Web technology. This Primer is on SPARQL and gives you a short introduction to its constructs ...

This slide set is a provided by the SESAM4 consortium as one out of three Technology Primers on Semantic Web technology. This Primer is on SPARQL and gives you a short introduction to its constructs followed by some examples. You can find the belonging slideset at youtube,

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  • Retorics: - where before information was locally managed, using local keys, and only accessible through customised interfaces using these “local keys” to identify information … … today this very same information is available from many different sources, represented in a standard way using globally unique identifiers … .. which are connected to each other and in such a way provide explicit key-references between different data-sets which can be used for automated harvesting and discovery
  • So now you think: - this is too large, too complex and too big. I cannot possible see how I can work with this and yes: I cannot see what is wrong with normal relational databases and SQL querying .. - well there is good and bad news. The good news is that it is indeed BIG, the bad news is that it is also complex and maybe even huge. … - But there is more good news: some smart people at W3C have found a way to let you use this graphs using a query language which is very similar to SQL, called SPARQL.

Sesam4   project presentation sparql - april 2011 Sesam4 project presentation sparql - april 2011 Presentation Transcript

  • NFR Verdikt Project n o 2342453 Semantic Technology SPARQL SPARQL Protocol And RDF Query Language Robert Engels
  • from local to global Information management in the digital age From Locally isolated ... ... to Globally interconnected
  • But What CAN you get out of this? View slide
    • What is SPARQL?
      • Query Language for interlinked graphs represented using RDF/OWL annotations View slide
      • SPARQL 1.0: W3C recommendation 2008
      • SPARQL 1.1: nearly a recommendation
    • Why SPARQL?
      • allows for querying RDF/OWL data & models
      • allows to define globally unambiguous queries
      • allows for distributed querying of datasets
      • query results can be merged automatically
    • Differences with SQL?
      • querying “graphs” instead of tables
      • local keys are replaced with global identifiers
      • tables need to provide the same schema, graphs do not
    • What can you do with SPARQL?
      • various result types
        • DESCRIBE, SELECT, ASK & CONSTRUCT
      • create result sets using known operators
        • a union of two sets (UNION)
        • a set representing the reverse of a statement (NOT)
        • … .
      • algoritmic operators like count, avg , & sum
        • specific to SPARQL 1.1
  • SPARQL - “DESCRIBE” Suppose The only thing you have is an Uri like this And no idea what is known about it.... http://data.esis.no/resource/projectID_111667 Simply send a SPARQL “DESCRIBE” to a sparql endpoint DESCRIBE <http://data.esis.no/resource/projectID_111667>
  • “ DESCRIBE” This node for me: Result of SPARQL - “DESCRIBE”
  • Result of SPARQL - “DESCRIBE” 1 1 1 1 1 2 2
  • SPARQL - “SElect” ... or you know what to look for and want to select specific resources. Send a sparql “select” to a sparql endpoint PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX dct: <http://purl.org/dc/terms/> PREFIX nfr: <http://data.esis.no/resource/> PREFIX foaf: <http://xmlns.com/foaf/0.1/> SELECT ?projectID ?projectName WHERE { ?projectID a foaf:Project ; dct:title ?projectName ; nfr:orgnrResponsibleOrg <https://ws.brreg.no/lod/enhet/962392687> . }
  • SPARQL - “SELECT”
  • RESULT SPARQL - “SELECT”
  • SPARQL - “CONSTRUCT” PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX dct: <http://purl.org/dc/terms/> PREFIX nfr: <http://data.esis.no/resource/> PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX funder: <http://research.data.gov.uk/def/project/> CONSTRUCT { ?projectID funder:title ?title } WHERE { ?projectID a foaf:Project; dct:title ?title ; nfr:orgnrResponsibleOrg <https://ws.brreg.no/lod/enhet/962392687> . } REPLACE NEW
  • SPARQL - “ASK” TRUE or FALSE? PREFIX nfr: <http://data.esis.no/resource/> ASK { ?projectID nfr:orgnrResponsibleOrg <https://ws.brreg.no/lod/enhet/962392687> }
  • Try it yourself! http://data.esis.no:2020/query.html http://opendata.computas.no:7001/joseki/
  • Further reading SPARQL 1.0 - W3C recommendation 2008 http://www.w3.org/TR/rdf-sparql-query/ SPARQL 1.1 – W3C SPARQL working group Wiki http://www.w3.org/2009/sparql/wiki/Main_Page Extensive tutorials by HP and Talis (and many others...) http://openjena.org/ARQ/Tutorial/index.html http://www.slideshare.net/ldodds/sparql-tutorial
  • www.sesam4.net