Sparql

  • 659 views
Uploaded on

SPARQL Language: A Short introduction

SPARQL Language: A Short introduction

More in: Education
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
No Downloads

Views

Total Views
659
On Slideshare
0
From Embeds
0
Number of Embeds
2

Actions

Shares
Downloads
22
Comments
0
Likes
1

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 1. SPARQL SPARQL Protocol and RDF Query Language S. Garlatti 16/01/14
  • 2. Outline  SPARQL page 2 Computer Science Department Semantic Web in Action
  • 3. SPARQL: SPARQL Protocol and RDF Query Language  SPARQL • pronounced "sparkle" [1]) is an RDF query language; its name is a recursive acronym that stands for SPARQL Protocol and RDF Query Language. It is standardized by the RDF Data Access Working Group (DAWG) of the World Wide Web Consortium, and is considered a component of the semantic web. • Initially released as a Candidate Recommendation in April 2006, but returned to Working Draft status in October 2006, due to two open issues. [2] In June 2007, SPARQL advanced to Candidate Recommendation once again. [3] On 12th November 2007 the status of SPARQL changed into Proposed Recommendation. [4] On 15th January 2008, SPARQL became an official W3C Recommendation. [5] page 3 Computer Science Department Semantic Web in Action
  • 4. SPARQL: SPARQL Protocol and RDF Query Language  SPARQL = • A Query Language • A Result Form • An Access Protocol page 4 Computer Science Department Linked Data & Social Web
  • 5. SPARQL: SPARQL Protocol and RDF Query Language  The Query Language: query forms • « Select » clause returns all or subset of the variables bound in a query pattern match • « Construct » returns an RDF graph constructed by substituting variables in a set of triple templates • « Ask » returns a boolean indicating whether a query pattern matches • « Describe » returns an RDF graph that describe the resources found page 5 Computer Science Department Linked Data & Social Web
  • 6. SPARQL: SPARQL Protocol and RDF Query Language « Select » equivalent to « SQL Select » returns a regular table Select … From … Identify data sources to query Where { … } The triple/graph pattern to be matched against the triple/graphs of RDF A conjunction of triples  PREFIX page 6 to declare the schema used in the query Computer Science Department Linked Data & Social Web
  • 7. SPARQL: SPARQL Protocol and RDF Query Language  PREFIX foaf: <http://xmlns.com/foaf/0.1/> SELECT ?name FROM <http://example.org/foaf/aliceFoaf> WHERE { ?x foaf:name ?name } Result: name « Alice » page 7 Computer Science Department Linked Data & Social Web
  • 8. SPARQL: SPARQL Protocol and RDF Query Language  PREFIX PREFIX PREFIX PREFIX foaf: <http://xmlns.com/foaf/0.1/> : <http://dbpedia.org/resource/> dbpedia2: <http://dbpedia.org/property/> dbpedia: <http://dbpedia.org/> SELECT distinct ?name ?birth ?person FROM <http://dbpedia.org/> WHERE  page 8 { ?person dbpedia2:birthPlace <http://dbpedia.org/resource/Berlin>. ?person dbpedia2:birth ?birth . ?person foaf:name ?name . } Computer Science Department Semantic Web in Action
  • 9. SPARQL: SPARQL Protocol and RDF Query Language  SPARQL  results: namebirthperson« ":Dru_Berrymore/birth/birth_date_and_age :Dru_Berrymore "Dru Berrymore"@de:Dru_Berrymore/birth/birth_date_and_age :Dru_Berrymore "Walter Benjamin"@de:Berlin :Walter_Benjamin "Walter Benjamin"@de:Germany :Walter_Benjamin Name Birth « Dru Berrymore » page 9 Computer Science Department Semantic Web in Action Person
  • 10. SPARQL: SPARQL Protocol and RDF Query Language   page 10 SELECT distinct ?name ?person FROM <http://dbpedia.org/> WHERE { ?person dbpedia2:birthPlace <http://dbpedia.org/resource/Berlin> . ?person foaf:name ?name . } SELECT distinct ?name ?birth ?death ?person FROM <http://dbpedia.org/> WHERE { ?person dbpedia2:birthPlace <http://dbpedia.org/resource/Berlin> . ?person dbpedia2:birth ?birth . ?person foaf:name ?name . ?person dbpedia2:death ?death. } Computer Science Department Semantic Web in Action
  • 11. SPARQL: SPARQL Protocol and RDF Query Language A constraint, expressed by the keyword “FILTER”, is a restriction on solutions over the whole group in which the filter appears  PREFIX dc: <http://purl.org/dc/elements/1.1/> PREFIX ns: <http://example.org/ns#> SELECT ?title ?price WHERE { ?x ns:price ?price . FILTER (?price < 30.5) ?x dc:title ?title . } page 11 Computer Science Department Linked Data & Social Web
  • 12. SPARQL: SPARQL Protocol and RDF Query Language  “regex” matches only plain literals with no language tag   page 12 { ?x foaf:name ?name . ?x foaf:mbox ?mbox . FILTER regex(?name, "Smith") } PREFIX dc: <http://purl.org/dc/elements/1.1/> SELECT ?title WHERE { ?x dc:title ?title FILTER regex(?title, "web", "i" ) } Computer Science Department Linked Data & Social Web
  • 13. SPARQL: SPARQL Protocol and RDF Query Language  Optional parts of the graph pattern may be specified syntactically with the “OPTIONAL” keyword applied to a graph pattern  page 13 SELECT distinct ?name ?birth ?death ?person FROM <http://dbpedia.org/> WHERE { ?person dbpedia2:birthPlace <http://dbpedia.org/resource/Berlin> . ?person dbpedia2:birth ?birth . ?person foaf:name ?name . OPTIONAL {?person dbpedia2:death ?death} } Computer Science Department Linked Data & Social Web
  • 14. SPARQL: SPARQL Protocol and RDF Query Language  Matching alternative • Pattern alternatives are syntactically specified with the  UNION keyword  SELECT distinct ?name ?birth ?death ?person WHERE { {?person dbpedia2:birthPlace <http://dbpedia.org/resource/Berlin> } UNION {?person dbpedia2:death ?death} ?person foaf:name ?name . ?person dbpedia2:birth ?birth . } page 14 Computer Science Department Linked Data & Social Web
  • 15. SPARQL: SPARQL Protocol and RDF Query Language  Sequence & Modify • « Order By » to sort,  • « LIMIT » result number,  • « OFFSET » rank of first result  SELECT distinct ?name ?person WHERE { ?person dbpedia2:birthPlace <http://dbpedia.org/resource/Berlin>. ?person foaf:name ?name. } ORDER BY ?name LIMIT 20 OFFSET 20 page 15 Computer Science Department Linked Data & Social Web
  • 16. SPARQL: SPARQL Protocol and RDF Query Language « Construct » • The CONSTRUCT query form returns a single RDF  graph specified by a graph template.  - The result is an RDF graph formed by taking each query  solution in the solution sequence, substituting for the  variables in the graph template, and combining the triples into  a single RDF graph by set union. • Useful for aggregating data from multiple sources  and merging it into a local store (from Ingenta) page 16 Computer Science Department Linked Data & Social Web
  • 17. SPARQL: SPARQL Protocol and RDF Query Language  PREFIX foaf: <http://xmlns.com/foaf/0.1/> FROM <http://molene.enstb.org/mlearning09/wpcontent/plugins/wp-rdfa/foaf.php CONSTRUCT { ?friend a foaf:Person; foaf:name ?name; foaf:homepage ?home.} WHERE { ?person foaf:mbox <mailto:ac@enstb.com>; foaf:knows ?friend. ?friend foaf:name ?name; foaf:homepage ?home.} page 17 Computer Science Department Linked Data & Social Web
  • 18. SPARQL: SPARQL Protocol and RDF Query Language  ASK • Returns a true/false value: test whether or not a query pattern  has a solution.  • No information is returned about the possible query solutions,  just whether or not a solution exists • Is there data that looks like this? Do you have any information  about that? (from Ingenta)  page 18 PREFIX foaf: <http://xmlns.com/foaf/0.1/> ASK WHERE { ?person a foaf:Person; foaf:mbox <mailto:ab@telecom-bretagne>. } Computer Science Department Semantic Web in Action
  • 19. SPARQL: SPARQL Protocol and RDF Query Language  DESCRIBE • The DESCRIBE form returns a single result RDF  graph containing RDF data about resources. • CONSTRUCT but with less control - Tell me about this or things that look like this … but you decide what’s relevant (from Ingenta)  PREFIX foaf: <http://xmlns.com/foaf/0.1/> DESCRIBE ?friend WHERE { ?person foaf:mbox “mailto:ab@telecom-bretagne”; foaf:knows ?friend.} page 19 Computer Science Department Semantic Web in Action
  • 20. SPARQL: SPARQL Protocol and RDF Query Language  Applied uses (from Ingenta) • DESCRIBE for Prototyping - DESCRIBE <http://example.org/someResource> - Quickly assembling Uis, Web APIs • SELECT for Indexing - Building an ordering over some data ORDER BY, LIMIT page 20 Computer Science Department Semantic Web in Action
  • 21. SPARQL: SPARQL Protocol and RDF Query Language  Applied uses (from Ingenta) • CONSTRUCT for transformation and also simple  inferencing - CONSTRUCT could be the XSLT of RDF - Currently limited by lack of expressions in CONSTRUCT  triple templates • ASK for validation • ASK – DESCRIBE – CONSTRUCT Pattern:  - Probe endpoint, Grab default view of data, Refine data extraction and/or  apply transformation page 21 Computer Science Department Semantic Web in Action
  • 22. SPARQL: SPARQL Protocol and RDF Query Language  SPARQL Protocol (from F. Gandon, INRIA) • Sending queries and their results accross the web  Example with HTTP binding • GET /sparql/?query=<encoded query> HTTP/1.1 Host: www.inria.fr User-agent: my-sparql-client/0.1 page 22 Computer Science Department Semantic Web in Action
  • 23. SPARQL: SPARQL Protocol and RDF Query Language  Example  with SOAP binding (from F. Gandon) <?xml version="1.0" encoding="UTF-8"?> <soapenv:Envelope xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <soapenv:Body> <query-request xmlns="http://www.w3.org/2005/09/sparqlprotocol-types/#"> <query> SELECT ?x ?p ?y WHERE {?x ?p ?y} </query> </query-request> </soapenv:Body> </soapenv:Envelope> page 23 Computer Science Department Semantic Web in Action
  • 24. SPARQL: SPARQL Protocol and RDF Query Language  Access to Data on the web • http://dbpedia.org/snorql/ • http://dbpedia.org/sparql • http://demo.openlinksw.com/rdfbrowser2/ • http://dataviewer.zitgist.com/ • Etc.  Twinkle : a sparql query tool • http://www.ldodds.com/projects/twinkle page 24 Computer Science Department Linked Data & Social Web
  • 25. SPARQL: SPARQL Protocol and RDF Query Language  Resources • http://en.wikipedia.org/wiki/SPARQL • http://www.w3.org/TR/rdf-sparql-query/ • http://jena.sourceforge.net/ARQ/Tutorial/ • http://esw.w3.org/topic/SparqlImplementations • http://arc.semsol.org/home • http://virtuoso.openlinksw.com/wiki/main/Main/ page 25 Computer Science Department Semantic Web in Action