A SPARQL query engine for querying over local and remote RDF files
npm install @comunica/query-sparql-file
Comunica SPARQL is a SPARQL query engine for JavaScript for querying local and remote RDF files.
This module is part of the Comunica framework.
``bash`
$ yarn global add @comunica/query-sparql-file
or
`bash`
$ npm install -g @comunica/query-sparql-file
Show 100 triples from a remote FOAF profile:
`bash`
$ comunica-sparql-file https://ruben.verborgh.org/profile/#me "CONSTRUCT WHERE { ?s ?p ?o } LIMIT 100"
Show 100 triples from a local RDF file:
`bash`
$ comunica-sparql-file path/to/my/file.ttl "CONSTRUCT WHERE { ?s ?p ?o } LIMIT 100"
Show all triples from a local and remote file:
`bash`
$ comunica-sparql-file path/to/my/file.ttl https://ruben.verborgh.org/profile/#me "CONSTRUCT WHERE { ?s ?p ?o } LIMIT 100"
Show the help with all options:
`bash`
$ comunica-sparql-file --help
Just like Comunica SPARQL,
a dynamic variant (comunica-dynamic-sparql-file) also exists.
_Read more about querying from the command line._
This engine can be used in JavaScript/TypeScript applications as follows:
`javascript
const QueryEngine = require('@comunica/query-sparql-file').QueryEngine;
const myEngine = new QueryEngine();
const bindingsStream = await myEngine.queryBindings(
SELECT ?s ?p ?o WHERE {
?s ?p
?s ?p ?o
} LIMIT 100, {
sources: ['http://fragments.dbpedia.org/2015/en'],
});
// Consume results as a stream (best performance)
bindingsStream.on('data', (binding) => {
console.log(binding.toString()); // Quick way to print bindings for testing
console.log(binding.has('s')); // Will be true
// Obtaining values
console.log(binding.get('s').value);
console.log(binding.get('s').termType);
console.log(binding.get('p').value);
console.log(binding.get('o').value);
});
bindingsStream.on('end', () => {
// The data-listener will not be called anymore once we get here.
});
bindingsStream.on('error', (error) => {
console.error(error);
});
// Consume results as async iterable (easier)
for await (const binding of bindingsStream) {
console.log(binding.toString());
}
// Consume results as an array (easier)
const bindings = await bindingsStream.toArray();
console.log(bindings[0].get('s').value);
console.log(bindings[0].get('s').termType);
`
_Read more about querying an application._
Start a webservice exposing http://fragments.dbpedia.org/2015-10/en via the SPARQL protocol, i.e., a _SPARQL endpoint_.
`bash`
$ comunica-sparql-file-http path/to/my/file.ttl
Show the help with all options:
`bash`
$ comunica-sparql-file-http --help
The SPARQL endpoint can only be started dynamically.
An alternative config file can be passed via the COMUNICA_CONFIG environment variable.
Use bin/http.js` when running in the Comunica monorepo development environment.