@comunica/actor-init-sparql-link-traversal

Comunica SPARQL Link Traversal Init Actor

Comunica SPARQL Link Traversal is a SPARQL query engine for JavaScript that follows links to detect new sources.

This module is part of the Comunica framework.

Install

$ yarn add @comunica/actor-init-sparql-link-traversal

or

$ npm install -g @comunica/actor-init-sparql-link-traversal

Usage

Show 100 triples from http://fragments.dbpedia.org/2015-10/en:

$ comunica-sparql-link-traversal https://www.rubensworks.net/ \
  "SELECT DISTINCT * WHERE {
       <https://www.rubensworks.net/#me> <http://xmlns.com/foaf/0.1/knows> ?p.
       <https://ruben.verborgh.org/profile/#me> <http://xmlns.com/foaf/0.1/knows> ?p.
       ?p <http://xmlns.com/foaf/0.1/name> ?name.
   }"

Show the help with all options:

$ comunica-sparql-link-traversal --help

Just like Comunica SPARQL, a dynamic variant (comunica-dynamic-sparql-link-traversal) also exists.

Read more about querying from the command line.

Usage within application

This engine can be used in JavaScript/TypeScript applications as follows:

const newEngine = require('@comunica/actor-init-sparql-link-traversal').newEngine;
const myEngine = newEngine();

const result = await myEngine.query(`
  SELECT DISTINCT * WHERE {
      <https://www.rubensworks.net/#me> <http://xmlns.com/foaf/0.1/knows> ?p.
      <https://ruben.verborgh.org/profile/#me> <http://xmlns.com/foaf/0.1/knows> ?p.
      ?p <http://xmlns.com/foaf/0.1/name> ?name.
  }`, {
  sources: ['https://www.rubensworks.net/'],
});

// Consume results as a stream (best performance)
result.bindingsStream.on('data', (binding) => {
    console.log(binding.get('?s').value);
    console.log(binding.get('?s').termType);

    console.log(binding.get('?p').value);

    console.log(binding.get('?o').value);
});

// Consume results as an array (easier)
const bindings = await result.bindings();
console.log(bindings[0].get('?s').value);
console.log(bindings[0].get('?s').termType);

Read more about querying an application.

Usage as a SPARQL endpoint

Start a webservice exposing http://fragments.dbpedia.org/2015-10/en via the SPARQL protocol, i.e., a SPARQL endpoint.

$ comunica-sparql-link-traversal-http https://www.rubensworks.net/

Show the help with all options:

$ comunica-sparql-link-traversal-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.

Read more about setting up a SPARQL endpoint.