oxigraph/js

Oxigraph for JavaScript

This package provides a JavaScript API on top of Oxigraph, compiled with WebAssembly.

Oxigraph is a graph database written in Rust implementing the SPARQL standard.

Oxigraph for JavaScript is a work in progress and currently offers a simple in-memory store with SPARQL 1.1 Query and SPARQL 1.1 Update capabilities.

The store is also able to load RDF serialized in Turtle, TriG, N-Triples, N-Quads and RDF/XML.

It is distributed using a a NPM package that should work with Node.JS 12+ and modern web browsers compatible with WebAssembly.

To install:

npm install oxigraph

To load with Node.JS:

const oxigraph = require('oxigraph');

or with ES modules:

import oxigraph from './node_modules/oxigraph/node.js';

To load on an HTML web page (for WebPack 5 remove the <script> tag and put the code in a JS file):

<script type="module">
    import init, * as oxigraph from './node_modules/oxigraph/web.js'

    (async function () {
        await init(); // Required to compile the WebAssembly code.

        // We can use here Oxigraph methods
    })()
</script>

Node.JS Example

Insert the triple <http://example/> <http://schema.org/name> "example" and log the name of <http://example/> in SPARQL:

const oxigraph = require('oxigraph');
const store = new oxigraph.Store();
const ex = oxigraph.namedNode("http://example/");
const schemaName = oxigraph.namedNode("http://schema.org/name");
store.add(oxigraph.triple(ex, schemaName, oxigraph.literal("example")));
for (const binding of store.query("SELECT ?name WHERE { <http://example/> <http://schema.org/name> ?name }")) {
    console.log(binding.get("name").value);
}

Web Example

Insert the triple <http://example/> <http://schema.org/name> "example" and log the name of <http://example/> in SPARQL:

<script type="module">
    import init, * as oxigraph from './node_modules/oxigraph/web.js'

    (async function () {
        await init(); // Required to compile the WebAssembly.

        const store = new oxigraph.Store();
        const ex = oxigraph.namedNode("http://example/");
        const schemaName = oxigraph.namedNode("http://schema.org/name");
        store.add(oxigraph.triple(ex, schemaName, oxigraph.literal("example")));
        for (const binding of store.query("SELECT ?name WHERE { <http://example/> <http://schema.org/name> ?name }")) {
            console.log(binding.get("name").value);
        }
    })()
</script>

This example works with WebPack too if you remove the <script> tag and put the code in a JS file.

API

Oxigraph currently provides a simple JS API.

RDF data model

Oxigraph implements the RDF/JS datamodel specification.

For that, the oxigraph module implements the RDF/JS DataFactory interface.

Example:

const oxigraph = require('oxigraph');
const ex = oxigraph.namedNode("http://example.com");
const blank = oxigraph.blankNode();
const foo = oxigraph.literal("foo");
const quad = oxigraph.quad(blank, ex, foo);

All terms overrides the the toString() method to return a N-Quads/SPARQL-like representation of the terms.

Store

Oxigraph API is centered around the Store class.

A store contains an RDF dataset and allows to query and update them using SPARQL.

Store(optional sequence<Quad>? quads) (constructor)

Creates a new store.

const oxigraph = require('oxigraph');
const store = new oxigraph.Store();

If provided, the Store will be initialized with a sequence of quads.

const oxigraph = require('oxigraph');
const store = new oxigraph.Store([oxigraph.quad(blank, ex, foo)]);

Store.prototype.add(Quad quad)

Inserts a quad in the store.

Example:

store.add(quad);

Store.prototype.delete(Quad quad)

Removes a quad from the store.

Example:

store.delete(quad);

Store.prototype.has(Quad quad)

Returns a boolean stating if the store contains the quad.

Example:

store.has(quad);

Store.prototype.match(optional Term? subject, optional Term? predicate, optional Term? object, optional Term? graph)

Returns an array with all the quads matching a given quad pattern.

Example to get all quads in the default graph with ex for subject:

store.match(ex, null, null, oxigraph.defaultGraph());

Example to get all quads:

store.match();

Store.prototype.query(String query)

Executes a SPARQL 1.1 Query. For SELECT queries the return type is an array of Map which keys are the bound variables and values are the values the result is bound to. For CONSTRUCT and ÐESCRIBE queries the return type is an array of Quad. For ASK queries the return type is a boolean.

Example of SELECT query:

for (binding of store.query("SELECT DISTINCT ?s WHERE { ?s ?p ?o }")) {
    console.log(binding.get("s").value);
}

Example of CONSTRUCT query:

const filteredStore = new oxigraph.Store(store.query("CONSTRUCT { <http:/example.com/> ?p ?o } WHERE { <http:/example.com/> ?p ?o }"));

Example of ASK query:

if (store.query("ASK { ?s ?s ?s }")) {
    console.log("there is a triple with same subject, predicate and object");
}

Store.prototype.update(String query)

Executes a SPARQL 1.1 Update. The LOAD operation is not supported yet.

Example of update:

store.update("DELETE WHERE { <http://example.com/s> ?p ?o }")

Store.prototype.load(String data, String mimeType, NamedNode|String? baseIRI, NamedNode|BlankNode|DefaultGraph? toNamedGraph)

Loads serialized RDF triples or quad into the store. The method arguments are:

1. data: the serialized RDF triples or quads.
2. mimeType: the MIME type of the serialization. See below for the supported mime types.
3. baseIRI: the base IRI to use to resolve the relative IRIs in the serialization.
4. toNamedGraph: for triple serialization formats, the name of the named graph the triple should be loaded to.

The available formats are:

• Turtle: text/turtle
• TriG: application/trig
• N-Triples: application/n-triples
• N-Quads: application/n-quads
• RDF/XML: application/rdf+xml

Example of loading a Turtle file into the named graph <http://example.com/graph> with the base IRI http://example.com:

store.load("<http://example.com> <http://example.com> <> .", "text/turtle", "http://example.com", oxigraph.namedNode("http://example.com/graph"));

Store.prototype.dump(String mimeType, NamedNode|BlankNode|DefaultGraph? fromNamedGraph)

Returns serialized RDF triples or quad from the store. The method arguments are:

1. mimeType: the MIME type of the serialization. See below for the supported mime types.
2. fromNamedGraph: for triple serialization formats, the name of the named graph the triple should be loaded from.

The available formats are:

• Turtle: text/turtle
• TriG: application/trig
• N-Triples: application/n-triples
• N-Quads: application/n-quads
• RDF/XML: application/rdf+xml

Example of building a Turtle file from the named graph <http://example.com/graph>:

store.dump("text/turtle", oxigraph.namedNode("http://example.com/graph"));

Migration guide

From 0.2 to 0.3

• The MemoryStore class is now called Store (there is no other kind of stores...).
• RDF/JS datamodel functions (namedNode...) are now available at the root of the oxigraph package. You now need to call oxigraph.namedNode instead of store.dataFactory.namedNode.
• RDF-star is now implemented. Quad is now a valid value for the Ωuad subject and object properties.

How to contribute

The Oxigraph bindings are written in Rust using the Rust WASM toolkit.

The The Rust Wasm Book is a great tutorial to get started.

To setup a dev environment:

• ensure to have a Rust toolchain with rustup and cargo installed (possible instructions).
• install wasm-pack: cargo install wasm-pack (it is also in some Linux distribution repositories).
• npm install to install pure JS dependencies.
• you are good to go!

Testing and linting:

• Rust code is formatted with rustfmt and linted with clippy. You can execute them with cargo fmt and cargo clippy.
• JS code is formatted and linted with Rome. npm run fmt to auto-format and npm test to lint and test.
• Tests are written in JavaScript using Mocha in the test directory. npm test to run them.

License

This project is licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Oxigraph by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.