rdf-parse

RDF Parse

This library parses RDF streams based on content type (or file name) and outputs RDF/JS-compliant quads as a stream.

This is useful in situations where you have RDF in some serialization, and you just need the parsed triples/quads, without having to concern yourself with picking the correct parser.

The following RDF serializations are supported:

Name	Content type	Extensions
TriG	application/trig	.trig
N-Quads	application/n-quads	.nq, .nquads
Turtle	text/turtle	.ttl, .turtle
N-Triples	application/n-triples	.nt, .ntriples
Notation3	text/n3	.n3
JSON-LD	application/ld+json, application/json	.json, .jsonld
RDF/XML	application/rdf+xml	.rdf, .rdfxml, .owl
RDFa and script RDF data tags HTML/XHTML	text/html, application/xhtml+xml	.html, .htm, .xhtml, .xht
Microdata	text/html, application/xhtml+xml	.html, .htm, .xhtml, .xht
RDFa in SVG/XML	image/svg+xml,application/xml	.xml, .svg, .svgz

Internally, this library makes use of RDF parsers from the Comunica framework, which enable streaming processing of RDF.

Internally, the following fully spec-compliant parsers are used:

• N3.js
• jsonld-streaming-parser.js
• microdata-rdf-streaming-parser.js
• rdfa-streaming-parser.js
• rdfxml-streaming-parser.js

Installation

$ npm install rdf-parse

or

$ yarn add rdf-parse

This package also works out-of-the-box in browsers via tools such as webpack and browserify.

Require

import rdfParser from "rdf-parse";

or

const rdfParser = require("rdf-parse").default;

Usage

Parsing by content type

The rdfParser.parse method takes in a text stream containing RDF in any serialization, and an options object, and outputs an RDFJS stream that emits RDF quads.

const textStream = require('streamify-string')(`
<http://ex.org/s> <http://ex.org/p> <http://ex.org/o1>, <http://ex.org/o2>.
`);

rdfParser.parse(textStream, { contentType: 'text/turtle', baseIRI: 'http://example.org' })
    .on('data', (quad) => console.log(quad))
    .on('error', (error) => console.error(error))
    .on('end', () => console.log('All done!'));

Parsing by file name

Sometimes, the content type of an RDF document may be unknown, for those cases, this library allows you to provide the path/URL of the RDF document, using which the extension will be determined.

For example, Turtle documents can be detected using the .ttl extension.

const textStream = require('streamify-string')(`
<http://ex.org/s> <http://ex.org/p> <http://ex.org/o1>, <http://ex.org/o2>.
`);

rdfParser.parse(textStream, { path: 'http://example.org/myfile.ttl', baseIRI: 'http://example.org' })
    .on('data', (quad) => console.log(quad))
    .on('error', (error) => console.error(error))
    .on('end', () => console.log('All done!'));

Getting all known content types

With rdfParser.getContentTypes(), you can retrieve a list of all content types for which a parser is available. Note that this method returns a promise that can be await-ed.

rdfParser.getContentTypesPrioritized() returns an object instead, with content types as keys, and numerical priorities as values.

// An array of content types
console.log(await rdfParser.getContentTypes());

// An object of prioritized content types
console.log(await rdfParser.getContentTypesPrioritized());

Obtaining prefixes

Using the 'prefix' event, you can obtain the prefixes that were available when parsing from documents in formats such as Turtle and TriG.

rdfParser.parse(textStream, { contentType: 'text/turtle' })
    .on('prefix', (prefix, iri) => console.log(prefix + ':' + iri))

Obtaining contexts

Using the 'context' event, you can obtain all contexts (@context) when parsing JSON-LD documents.

Multiple contexts can be found, and the context values that are emitted correspond exactly to the context value as included in the JSON-LD document.

rdfParser.parse(textStream, { contentType: 'application/ld+json' })
    .on('context', (context) => console.log(context))

License

This software is written by Ruben Taelman.

This code is released under the MIT license.