sparql_client:sparql

/usr/lib/swi-prolog/library/semweb/sparql_client.pl

sparql_query(+Query, -Result, +Options) is nondet

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])
                ]).