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oxigraph/js/README.md

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Oxigraph for JavaScript
=======================
[![npm](https://img.shields.io/npm/v/oxigraph)](https://www.npmjs.com/package/oxigraph)
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This package provides a JavaScript API on top of [Oxigraph](https://crates.io/crates/oxigraph), compiled with WebAssembly.
Oxigraph is a graph database written in Rust implementing the [SPARQL](https://www.w3.org/TR/sparql11-overview/) standard.
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.
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/).
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.
To install:
```bash
npm install oxigraph
```
To load with Node.JS:
```js
const oxigraph = require('oxigraph');
```
or with ES modules:
```js
import oxigraph from './node_modules/oxigraph/node.js';
```
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):
```html
<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:
```js
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:
```html
<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](https://rdf.js.org/data-model-spec/).
For that, the `oxigraph` module implements the [RDF/JS `DataFactory` interface](http://rdf.js.org/data-model-spec/#datafactory-interface).
Example:
```js
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](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-dataset) and allows to query and update them using SPARQL.
#### `Store(optional sequence<Quad>? quads)` (constructor)
Creates a new store.
```js
const oxigraph = require('oxigraph');
const store = new oxigraph.Store();
```
If provided, the `Store` will be initialized with a sequence of quads.
```js
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:
```js
store.add(quad);
```
#### `Store.prototype.delete(Quad quad)`
Removes a quad from the store.
Example:
```js
store.delete(quad);
```
#### `Store.prototype.has(Quad quad)`
Returns a boolean stating if the store contains the quad.
Example:
```js
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:
```js
store.match(ex, null, null, oxigraph.defaultGraph());
```
Example to get all quads:
```js
store.match();
```
#### `Store.prototype.query(String query)`
Executes a [SPARQL 1.1 Query](https://www.w3.org/TR/sparql11-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:
```js
for (binding of store.query("SELECT DISTINCT ?s WHERE { ?s ?p ?o }")) {
console.log(binding.get("s").value);
}
```
Example of CONSTRUCT query:
```js
const filteredStore = new oxigraph.Store(store.query("CONSTRUCT { <http:/example.com/> ?p ?o } WHERE { <http:/example.com/> ?p ?o }"));
```
Example of ASK query:
```js
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](https://www.w3.org/TR/sparql11-update/).
The [`LOAD` operation](https://www.w3.org/TR/sparql11-update/#load) is not supported yet.
Example of update:
```js
store.update("DELETE WHERE { <http://example.com/s> ?p ?o }")
```
#### `Store.prototype.load(String data, String format, 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. `format`: the format of the serialization. See below for the supported formats.
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](https://www.w3.org/TR/turtle/): `text/turtle` or `ttl`
* [TriG](https://www.w3.org/TR/trig/): `application/trig` or `trig`
* [N-Triples](https://www.w3.org/TR/n-triples/): `application/n-triples` or `nt`
* [N-Quads](https://www.w3.org/TR/n-quads/): `application/n-quads` or `nq`
* [N3](https://w3c.github.io/N3/spec/): `text/n3` or `n3`
* [RDF/XML](https://www.w3.org/TR/rdf-syntax-grammar/): `application/rdf+xml` or `rdf`
Example of loading a Turtle file into the named graph `<http://example.com/graph>` with the base IRI `http://example.com`:
```js
store.load("<http://example.com> <http://example.com> <> .", "text/turtle", "http://example.com", oxigraph.namedNode("http://example.com/graph"));
```
#### `Store.prototype.dump(String format, NamedNode|BlankNode|DefaultGraph? fromNamedGraph)`
Returns serialized RDF triples or quad from the store.
The method arguments are:
1. `format`: the format type of the serialization. See below for the supported types.
2. `fromNamedGraph`: for triple serialization formats, the name of the named graph the triple should be loaded from.
The available formats are:
* [Turtle](https://www.w3.org/TR/turtle/): `text/turtle` or `ttl`
* [TriG](https://www.w3.org/TR/trig/): `application/trig` or `trig`
* [N-Triples](https://www.w3.org/TR/n-triples/): `application/n-triples` or `nt`
* [N-Quads](https://www.w3.org/TR/n-quads/): `application/n-quads` or `nq`
* [N3](https://w3c.github.io/N3/spec/): `text/n3` or `n3`
* [RDF/XML](https://www.w3.org/TR/rdf-syntax-grammar/): `application/rdf+xml` or `rdf`
Example of building a Turtle file from the named graph `<http://example.com/graph>`:
```js
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](https://w3c.github.io/rdf-star/cg-spec/2021-12-17.html) 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](https://rustwasm.github.io/docs.html).
The [The Rust Wasm Book](https://rustwasm.github.io/docs/book/) is a great tutorial to get started.
To run the tests of the JS bindings written in JS run `npm test`.
## License
This project is licensed under either of
* Apache License, Version 2.0, ([LICENSE-APACHE](../LICENSE-APACHE) or
http://www.apache.org/licenses/LICENSE-2.0)
* MIT license ([LICENSE-MIT](../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.