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SPARQL 1.2 Protocol Client Implementation

sparqlx aims to provide a convenient Python interface for interacting with SPARQL endpoints according to the SPARQL 1.2 Protocol.

The SPARQL Protocol provides a specification for HTTP operations targeting SPARQL Query and Update endpoints.

"[The SPARQL 1.2 Protocol] describes a means for conveying SPARQL queries and updates to a SPARQL processing service and returning the results via HTTP to the entity that requested them." (SPARQL 1.2 Protocol - Abstract)

Generally, the SPARQL 1.2 Protocol defines the following HTTP operations for SPARQL operations:

  • GET (query)
  • URL-encoded POST (query and update)
  • POST directly (query and update)

See 2.2 Query Operation and 2.3 Update Operation.

sparqlx uses URL-encoded POST for both Query and Update operations by default.

This allows to send a Request Content Type in the Accept Header and both the Query/Update Request strings and Query/Update Parameters in the Request Message Body.

sparqlx also implements GET (for query operations) and POST-direct (for query and update operations); the SPARQL Operation method can be set via the query_method: typing.Literal["GET", "POST", "POST-direct"] and update_method: typing.Literal["POST", "POST-direct"] parameters in the SPARQLWrapper class.

SPARQL Protocol Request Parameters

The SPARQL Protocol also specifies the following request parameters:

  • version (0 or 1)
  • default-graph-uri (0 or more)
  • named-graph-uri (0 or more)

for Query Operations, where default-graph-uri and named-graph-uri correspond to SPARQL FROM and FROM NAMED respectively, and, if present, take precedence over SPARQL clauses.

  • version (0 or 1)
  • using-graph-uri (0 or more)
  • using-named-graph-uri (0 or more)

for Update Operations, where using-graph-uri and using-named-graph-uri correspond to SPARQL USING and USING NAMED, and likewise take precedence over SPARQL clauses.

SPARQL Protocol request parameters are reflected in the sparqlx API:

  • Methods implementing query operations take default_graph_uri and named_graph_uri parameters.
  • Methods implementing udpate operations take using_graph_uri and using_named_graph_uri parameters.
  • Both query and update methods take a version parameter.