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SPARQL
SPARQL (pronounced "sparkle", a recursive acronym for SPARQL Protocol and RDF Query Language) is an RDF query language—that is, a semantic query language for databases—able to retrieve and manipulate data stored in Resource Description Framework (RDF) format. It was made a standard by the RDF Data Access Working Group (DAWG) of the World Wide Web Consortium, and is recognized as one of the key technologies of the semantic web. On 15 January 2008, SPARQL 1.0 was acknowledged by W3C as an official recommendation, and SPARQL 1.1 in March, 2013.
SPARQL allows for a query to consist of triple patterns, conjunctions, disjunctions, and optional patterns.
Implementations for multiple programming languages exist. There exist tools that allow one to connect and semi-automatically construct a SPARQL query for a SPARQL endpoint, for example ViziQuer. In addition, tools exist to translate SPARQL queries to other query languages, for example to SQL and to XQuery.
SPARQL allows users to write queries that follow the RDF specification of the W3C. Thus, the entire dataset is "subject-predicate-object" triples. Subjects and predicates are always URI identifiers, but objects can be URIs or literal values. This single physical schema of 3 "columns" is hypernormalized in that what would be 1 relational record with (for example) 4 columns is now 4 triples with the subject being repeated over and over, the predicate essentially being the column name, and the object being the column value. Although this seems unwieldy, the SPARQL syntax offers these features:
1. Subjects and Objects can be used to find the other including transitively.
Below is a set of triples. It should be clear that
ex:sw001 and ex:sw002 link to ex:sw003, which itself has links:
In SPARQL, the first time a variable is encountered in the expression pipeline, it is populated with result. The second and subsequent times it is seen, it is used as an input. If we assign ("bind") the URI ex:sw003 to the ?targets variable, then it drives a
result into ?src; this tells us all the things that link to ex:sw003 (upstream dependency):
But with a simple switch of the binding variable, the behavior is reversed. This will produce all the things upon which ex:sw003 depends (downstream dependency):
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SPARQL AI simulator
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SPARQL
SPARQL (pronounced "sparkle", a recursive acronym for SPARQL Protocol and RDF Query Language) is an RDF query language—that is, a semantic query language for databases—able to retrieve and manipulate data stored in Resource Description Framework (RDF) format. It was made a standard by the RDF Data Access Working Group (DAWG) of the World Wide Web Consortium, and is recognized as one of the key technologies of the semantic web. On 15 January 2008, SPARQL 1.0 was acknowledged by W3C as an official recommendation, and SPARQL 1.1 in March, 2013.
SPARQL allows for a query to consist of triple patterns, conjunctions, disjunctions, and optional patterns.
Implementations for multiple programming languages exist. There exist tools that allow one to connect and semi-automatically construct a SPARQL query for a SPARQL endpoint, for example ViziQuer. In addition, tools exist to translate SPARQL queries to other query languages, for example to SQL and to XQuery.
SPARQL allows users to write queries that follow the RDF specification of the W3C. Thus, the entire dataset is "subject-predicate-object" triples. Subjects and predicates are always URI identifiers, but objects can be URIs or literal values. This single physical schema of 3 "columns" is hypernormalized in that what would be 1 relational record with (for example) 4 columns is now 4 triples with the subject being repeated over and over, the predicate essentially being the column name, and the object being the column value. Although this seems unwieldy, the SPARQL syntax offers these features:
1. Subjects and Objects can be used to find the other including transitively.
Below is a set of triples. It should be clear that
ex:sw001 and ex:sw002 link to ex:sw003, which itself has links:
In SPARQL, the first time a variable is encountered in the expression pipeline, it is populated with result. The second and subsequent times it is seen, it is used as an input. If we assign ("bind") the URI ex:sw003 to the ?targets variable, then it drives a
result into ?src; this tells us all the things that link to ex:sw003 (upstream dependency):
But with a simple switch of the binding variable, the behavior is reversed. This will produce all the things upon which ex:sw003 depends (downstream dependency):