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270 lines
9.7 KiB
270 lines
9.7 KiB
Oxigraph for JavaScript
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=======================
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[](https://www.npmjs.com/package/oxigraph)
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[](https://github.com/oxigraph/oxigraph/actions)
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[](https://gitter.im/oxigraph/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
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This package provides a JavaScript API on top of [Oxigraph](https://crates.io/crates/oxigraph), compiled with WebAssembly.
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Oxigraph is a graph database written in Rust implementing the [SPARQL](https://www.w3.org/TR/sparql11-overview/) standard.
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Oxigraph for JavaScript is a work in progress and currently offers a simple in-memory store with [SPARQL 1.1 Query](https://www.w3.org/TR/sparql11-query/) and [SPARQL 1.1 Update](https://www.w3.org/TR/sparql11-update/) capabilities.
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The store is also able to load RDF serialized in [Turtle](https://www.w3.org/TR/turtle/), [TriG](https://www.w3.org/TR/trig/), [N-Triples](https://www.w3.org/TR/n-triples/), [N-Quads](https://www.w3.org/TR/n-quads/) and [RDF/XML](https://www.w3.org/TR/rdf-syntax-grammar/).
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It is distributed using a [a NPM package](https://www.npmjs.com/package/oxigraph) that should work with Node.JS 12+ and modern web browsers compatible with WebAssembly.
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To install:
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```bash
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npm install oxigraph
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```
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To load with Node.JS:
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```js
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const oxigraph = require('oxigraph');
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```
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or with ES modules:
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```js
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import oxigraph from './node_modules/oxigraph/node.js';
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```
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To load on an HTML web page (for [WebPack 5](https://webpack.js.org/) remove the `<script>` tag and put the code in a JS file):
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```html
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<script type="module">
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import init, * as oxigraph from './node_modules/oxigraph/web.js'
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(async function () {
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await init(); // Required to compile the WebAssembly code.
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// We can use here Oxigraph methods
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})()
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</script>
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```
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## Node.JS Example
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Insert the triple `<http://example/> <http://schema.org/name> "example"` and log the name of `<http://example/>` in SPARQL:
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```js
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const oxigraph = require('oxigraph');
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const store = new oxigraph.Store();
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const ex = oxigraph.namedNode("http://example/");
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const schemaName = oxigraph.namedNode("http://schema.org/name");
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store.add(oxigraph.triple(ex, schemaName, oxigraph.literal("example")));
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for (const binding of store.query("SELECT ?name WHERE { <http://example/> <http://schema.org/name> ?name }")) {
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console.log(binding.get("name").value);
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}
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```
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## Web Example
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Insert the triple `<http://example/> <http://schema.org/name> "example"` and log the name of `<http://example/>` in
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SPARQL:
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```html
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<script type="module">
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import init, * as oxigraph from './node_modules/oxigraph/web.js'
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(async function () {
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await init(); // Required to compile the WebAssembly.
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const store = new oxigraph.Store();
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const ex = oxigraph.namedNode("http://example/");
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const schemaName = oxigraph.namedNode("http://schema.org/name");
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store.add(oxigraph.triple(ex, schemaName, oxigraph.literal("example")));
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for (const binding of store.query("SELECT ?name WHERE { <http://example/> <http://schema.org/name> ?name }")) {
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console.log(binding.get("name").value);
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}
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})()
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</script>
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```
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This example works with WebPack too if you remove the `<script>` tag and put the code in a JS file.
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## API
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Oxigraph currently provides a simple JS API.
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### RDF data model
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Oxigraph implements the [RDF/JS datamodel specification](https://rdf.js.org/data-model-spec/).
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For that, the `oxigraph` module implements the [RDF/JS `DataFactory` interface](http://rdf.js.org/data-model-spec/#datafactory-interface).
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Example:
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```js
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const oxigraph = require('oxigraph');
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const ex = oxigraph.namedNode("http://example.com");
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const blank = oxigraph.blankNode();
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const foo = oxigraph.literal("foo");
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const quad = oxigraph.quad(blank, ex, foo);
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```
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All terms overrides the the `toString()` method to return a N-Quads/SPARQL-like representation of the terms.
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### `Store`
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Oxigraph API is centered around the `Store` class.
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A store contains an [RDF dataset](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-dataset) and allows to query and update them using SPARQL.
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#### `Store(optional sequence<Quad>? quads)` (constructor)
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Creates a new store.
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```js
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const oxigraph = require('oxigraph');
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const store = new oxigraph.Store();
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```
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If provided, the `Store` will be initialized with a sequence of quads.
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```js
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const oxigraph = require('oxigraph');
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const store = new oxigraph.Store([oxigraph.quad(blank, ex, foo)]);
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```
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#### `Store.prototype.add(Quad quad)`
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Inserts a quad in the store.
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Example:
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```js
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store.add(quad);
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```
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#### `Store.prototype.delete(Quad quad)`
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Removes a quad from the store.
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Example:
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```js
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store.delete(quad);
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```
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#### `Store.prototype.has(Quad quad)`
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Returns a boolean stating if the store contains the quad.
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Example:
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```js
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store.has(quad);
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```
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#### `Store.prototype.match(optional Term? subject, optional Term? predicate, optional Term? object, optional Term? graph)`
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Returns an array with all the quads matching a given quad pattern.
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Example to get all quads in the default graph with `ex` for subject:
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```js
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store.match(ex, null, null, oxigraph.defaultGraph());
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```
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Example to get all quads:
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```js
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store.match();
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```
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#### `Store.prototype.query(String query)`
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Executes a [SPARQL 1.1 Query](https://www.w3.org/TR/sparql11-query/).
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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.
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For `CONSTRUCT` and `ÐESCRIBE` queries the return type is an array of `Quad`.
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For `ASK` queries the return type is a boolean.
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Example of SELECT query:
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```js
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for (binding of store.query("SELECT DISTINCT ?s WHERE { ?s ?p ?o }")) {
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console.log(binding.get("s").value);
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}
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```
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Example of CONSTRUCT query:
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```js
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const filteredStore = new oxigraph.Store(store.query("CONSTRUCT { <http:/example.com/> ?p ?o } WHERE { <http:/example.com/> ?p ?o }"));
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```
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Example of ASK query:
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```js
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if (store.query("ASK { ?s ?s ?s }")) {
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console.log("there is a triple with same subject, predicate and object");
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}
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```
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#### `Store.prototype.update(String query)`
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Executes a [SPARQL 1.1 Update](https://www.w3.org/TR/sparql11-update/).
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The [`LOAD` operation](https://www.w3.org/TR/sparql11-update/#load) is not supported yet.
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Example of update:
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```js
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store.update("DELETE WHERE { <http://example.com/s> ?p ?o }")
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```
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#### `Store.prototype.load(String data, String mimeType, NamedNode|String? baseIRI, NamedNode|BlankNode|DefaultGraph? toNamedGraph)`
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Loads serialized RDF triples or quad into the store.
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The method arguments are:
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1. `data`: the serialized RDF triples or quads.
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2. `mimeType`: the MIME type of the serialization. See below for the supported mime types.
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3. `baseIRI`: the base IRI to use to resolve the relative IRIs in the serialization.
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4. `toNamedGraph`: for triple serialization formats, the name of the named graph the triple should be loaded to.
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The available formats are:
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* [Turtle](https://www.w3.org/TR/turtle/): `text/turtle`
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* [TriG](https://www.w3.org/TR/trig/): `application/trig`
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* [N-Triples](https://www.w3.org/TR/n-triples/): `application/n-triples`
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* [N-Quads](https://www.w3.org/TR/n-quads/): `application/n-quads`
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* [RDF/XML](https://www.w3.org/TR/rdf-syntax-grammar/): `application/rdf+xml`
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Example of loading a Turtle file into the named graph `<http://example.com/graph>` with the base IRI `http://example.com`:
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```js
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store.load("<http://example.com> <http://example.com> <> .", "text/turtle", "http://example.com", oxigraph.namedNode("http://example.com/graph"));
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```
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#### `Store.prototype.dump(String mimeType, NamedNode|BlankNode|DefaultGraph? fromNamedGraph)`
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Returns serialized RDF triples or quad from the store.
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The method arguments are:
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1. `mimeType`: the MIME type of the serialization. See below for the supported mime types.
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2. `fromNamedGraph`: for triple serialization formats, the name of the named graph the triple should be loaded from.
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The available formats are:
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* [Turtle](https://www.w3.org/TR/turtle/): `text/turtle`
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* [TriG](https://www.w3.org/TR/trig/): `application/trig`
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* [N-Triples](https://www.w3.org/TR/n-triples/): `application/n-triples`
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* [N-Quads](https://www.w3.org/TR/n-quads/): `application/n-quads`
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* [RDF/XML](https://www.w3.org/TR/rdf-syntax-grammar/): `application/rdf+xml`
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Example of building a Turtle file from the named graph `<http://example.com/graph>`:
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```js
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store.dump("text/turtle", oxigraph.namedNode("http://example.com/graph"));
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```
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## Migration guide
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### From 0.2 to 0.3
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* The `MemoryStore` class is now called `Store` (there is no other kind of stores...).
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* 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`.
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* [RDF-star](https://w3c.github.io/rdf-star/cg-spec) is now implemented. `Quad` is now a valid value for the `Ωuad` `subject` and `object` properties.
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## How to contribute
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The Oxigraph bindings are written in Rust using [the Rust WASM toolkit](https://rustwasm.github.io/docs.html).
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The [The Rust Wasm Book](https://rustwasm.github.io/docs/book/) is a great tutorial to get started.
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To run the tests of the JS bindings written in JS run `npm test`.
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## License
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This project is licensed under either of
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* Apache License, Version 2.0, ([LICENSE-APACHE](../LICENSE-APACHE) or
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http://www.apache.org/licenses/LICENSE-2.0)
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* MIT license ([LICENSE-MIT](../LICENSE-MIT) or
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http://opensource.org/licenses/MIT)
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at your option.
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### Contribution
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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.
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