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10 library(semweb/sparql_client): SPARQL client library
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  • Documentation
    • Reference manual
    • Packages
      • SWI-Prolog Semantic Web Library 3.0
        • library(semweb/sparql_client): SPARQL client library
          • sparql_query/3
          • sparql_set_server/1
          • sparql_read_xml_result/2
          • sparql_read_json_result/2
Availability::- use_module(library(semweb/sparql_client)).
Source[nondet]sparql_query(+Query, -Result, +Options)
Execute a SPARQL query on an HTTP SPARQL endpoint. Query is an atom that denotes the query. Result is unified to a term rdf(S,P,O) for CONSTRUCT and DESCRIBE queries, row(...) for SELECT queries and true or false for ASK queries. Options are
host(+Host)
port(+Port)
path(+Path)
scheme(+Scheme)
The above four options set the location of the server.
search(+ListOfParams)
Provide additional query parameters, such as the graph.
variable_names(-ListOfNames)
Unifies ListOfNames with a list of atoms that describe the names of the variables in a SELECT query.

Remaining options are passed to http_open/3. The defaults for Host, Port and Path can be set using sparql_set_server/1. The initial default for port is 80 and path is /sparql/.

For example, the ClioPatria server understands the parameter entailment. The code below queries for all triples using _rdfs_entailment.

?- sparql_query('select * where { ?s ?p ?o }',
                Row,
                [ search([entailment=rdfs])
                ]).
ClioPatria (version V3.1.1-21-gb8003bb)