quadstore-sparql

quadstore-sparql

quadstore-sparql is a SPARQL engine for quadstore.

Credits

quadstore-sparql is basically a wrapper around a specific configuration of the Comunica engine framework.

All credit goes to the wonderful team maintaining Comunica.

Current version

Current version: v6.0.0 [See on NPM].

quadstore-sparql is maintained alongside quadstore and versioned accordingly. Equal major version numbers imply compatibility between the two modules.

Notes

• Uses Semantic Versioning. Pre-releases are tagged accordingly.
• The master branch is kept in sync with NPM and all development work happens on the devel branch and/or issue-specific branches.
• Requires Node.js >= 8.0.0.

Usage

SparqlEngine()

The constructor expects an instance of quadstore.RdfStore as its only argument.

const memdown = require('memdown');
const quadstore = require('quadstore');
const SparqlEngine = require('quadstore-sparql');

const rdfStoreInstance = new quadstore.RdfStore(memdown());
const sparqlEngineInstance = new SparqlEngine(store);

rdfStoreInstance.import();
sparqlEngineInstance.query('SELECT * WHERE {?s ?p ?o}', (err, result) => { 
  /* ... */
});

SparqlEngine.prototype.query()

The .query() method takes care of calling the .queryStream() method and then buffering all data emitted by the stream.

const queryString = 'SELECT *  WHERE { GRAPH ?g { ?s ?p ?o } }';
const resultFormat = 'application/sparql-results+xml';

const result = await sparqlEngineInstance.queryStream(queryString, resultFormat);
console.log(result);

Depending on the format argument, the returned item is either an array of quads/bindings or a string.

SparqlEngine.prototype.queryStream()

const queryString = 'SELECT *  WHERE { GRAPH ?g { ?s ?p ?o } }';
const resultFormat = 'application/sparql-results+xml';

const resultStream = await sparqlEngineInstance.queryStream(queryString, resultFormat);
resultStream.on('data', (chunk) => { /* ... */ });

Returns a stream.Readable that outputs the results of the query, formatted according to the data format specified as the second argument.

Format	Datatype of emitted chunks
nil	dictionary of bindings as RDF/JS' Term instances
comunica	raw @comunica/actor-init-sparql-rdfjs' result object
application/json	simple JSON serialization
application/sparql-results+xml	SPARQL-XML
application/sparql-results+json	SPARQL-JSON
application/trig	Trig
application/n-quads	N-Quads

Browser

For in-browser usage refer to quadstore's instructions on the same topic. This package uses @comunica/actor-init-sparql-rdfjs, which is a hefty package. Expect bundle sizes in the 1 - 2 MB range.