1. SPARQL SPARQL Protocol and RDF Query Language
03/09/2018

2. Outline
SPARQL
Semantic Web in Action

3. SPARQL: SPARQL Protocol and RDF Query Language
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]
Semantic Web in Action

4. SPARQL: SPARQL Protocol and RDF Query Language
A Query Language
A Result Form
An Access Protocol
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
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 to declare the schema used in the query
Linked Data & Social Web

7. SPARQL: SPARQL Protocol and RDF Query Language
PREFIX foaf: < SELECT ?name FROM < WHERE { ?x foaf:name ?name } Result:
name
« Alice »
Linked Data & Social Web

8. SPARQL: SPARQL Protocol and RDF Query Language
PREFIX foaf: < PREFIX : < PREFIX dbpedia2: < PREFIX dbpedia: < SELECT distinct ?name ?birth ?person FROM < WHERE
{ ?person dbpedia2:birthPlace <
?person dbpedia2:birth ?birth .
?person foaf:name ?name . }
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 :Dru_Berrymore "Walter :Walter_Benjamin "Walter :Walter_Benjamin
Name
Birth
Person
« Dru Berrymore »
Semantic Web in Action

10. SPARQL: SPARQL Protocol and RDF Query Language
SELECT distinct ?name ?person FROM < WHERE { ?person dbpedia2:birthPlace < ?person foaf:name ?name . }
SELECT distinct ?name ?birth ?death ?person FROM < WHERE { ?person dbpedia2:birthPlace < ?person dbpedia2:birth ?birth ?person foaf:name ?name ?person dbpedia2:death ?death. }
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: < PREFIX ns: < SELECT ?title ?price WHERE { ?x ns:price ?price FILTER (?price < 30.5) ?x dc:title ?title . }
Linked Data & Social Web

12. SPARQL: SPARQL Protocol and RDF Query Language
“regex” matches only plain literals with no language tag
{  ?x foaf:name ?name ?x foaf:mbox ?mbox FILTER regex(?name, "Smith") }
PREFIX dc: < SELECT ?title WHERE { ?x dc:title ?title FILTER regex(?title, "web", "i" ) }
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
SELECT distinct ?name ?birth ?death ?person FROM < WHERE { ?person dbpedia2:birthPlace < ?person dbpedia2:birth ?birth ?person foaf:name ?name OPTIONAL {?person dbpedia2:death ?death} }
Linked Data & Social Web

14. 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 < ?person foaf:name ?name. } ORDER BY ?name LIMIT 20 OFFSET 20
Linked Data & Social Web

15. 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
Linked Data & Social Web

16. SPARQL: SPARQL Protocol and RDF Query Language
PREFIX foaf: < FROM < content/plugins/wp-rdfa/foaf.php CONSTRUCT { ?friend a foaf:Person; foaf:name ?name; foaf:homepage ?home.} WHERE { ?person foaf:mbox foaf:knows ?friend. ?friend foaf:name ?name; foaf:homepage ?home.}
Linked Data & Social Web

17. 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)
PREFIX foaf: < ASK WHERE { ?person a foaf:Person; foaf:mbox }
Semantic Web in Action

18. 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
PREFIX foaf: < DESCRIBE ?friend WHERE { ?person foaf:mbox foaf:knows ?friend.}
Semantic Web in Action

19. SPARQL: SPARQL Protocol and RDF Query Language
Applied uses
DESCRIBE for Prototyping
DESCRIBE <
Quickly assembling Uis, Web APIs
SELECT for Indexing
Building an ordering over some data ORDER BY, LIMIT
Semantic Web in Action

20. SPARQL: SPARQL Protocol and RDF Query Language
Applied uses
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
Semantic Web in Action

21. SPARQL: SPARQL Protocol and RDF Query Language
Access to Data on the web
Etc.
Twinkle : a sparql query tool
Linked Data & Social Web

22. SPARQL: SPARQL Protocol and RDF Query Language
Resources
Semantic Web in Action