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

Outline SPARQL Semantic Web in Action

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

SPARQL: SPARQL Protocol and RDF Query Language A Query Language A Result Form An Access Protocol Linked Data & Social Web

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

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

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 » Linked Data & Social Web

SPARQL: SPARQL Protocol and RDF Query Language PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX : <http://dbpedia.org/resource/> PREFIX dbpedia2: <http://dbpedia.org/property/> PREFIX dbpedia: <http://dbpedia.org/> SELECT distinct ?name ?birth ?person FROM <http://dbpedia.org/> WHERE { ?person dbpedia2:birthPlace <http://dbpedia.org/resource/Berlin>. ?person dbpedia2:birth ?birth . ?person foaf:name ?name . } Semantic Web in Action

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 Person « Dru Berrymore » Semantic Web in Action

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

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 . } Linked Data & Social Web

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: <http://purl.org/dc/elements/1.1/> SELECT ?title WHERE { ?x dc:title ?title FILTER regex(?title, "web", "i" ) } Linked Data & Social Web

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 <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} } Linked Data & Social Web

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 Linked Data & Social Web

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

SPARQL: SPARQL Protocol and RDF Query Language PREFIX foaf: <http://xmlns.com/foaf/0.1/> FROM <http://molene.enstb.org/mlearning09/wp- content/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.} Linked Data & Social Web

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: <http://xmlns.com/foaf/0.1/> ASK WHERE { ?person a foaf:Person; foaf:mbox <mailto:ab@telecom-bretagne>. } Semantic Web in Action

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: <http://xmlns.com/foaf/0.1/> DESCRIBE ?friend WHERE { ?person foaf:mbox “mailto:ab@telecom-bretagne”; foaf:knows ?friend.} Semantic Web in Action

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

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

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 Linked Data & Social Web

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/ Semantic Web in Action