nextgraph-rs/README.md

Oxigraph

Oxigraph is a graph database library implementing the SPARQL standard.

Its goal is to provide a compliant, safe and fast on-disk graph database. It also provides a set of utility functions for reading, writing, and processing RDF files.

Oxigraph is in heavy development and SPARQL query evaluation has not been optimized yet.

Oxigraph also provides a CLI tool and a Python library based on this library.

Oxigraph implements the following specifications:

• SPARQL 1.1 Query, SPARQL 1.1 Update, and SPARQL 1.1 Federated Query.
• Turtle, TriG, N-Triples, N-Quads, and RDF/XML RDF serialization formats for both data ingestion and retrieval.
• SPARQL Query Results XML Format, SPARQL 1.1 Query Results JSON Format and SPARQL 1.1 Query Results CSV and TSV Formats.

A preliminary benchmark is provided. Oxigraph internal design is described on the wiki.

The main entry point of Oxigraph is the Store struct:

use oxigraph::store::Store;
use oxigraph::model::*;
use oxigraph::sparql::QueryResults;

let store = Store::new().unwrap();

// insertion
let ex = NamedNode::new("http://example.com").unwrap();
let quad = Quad::new(ex.clone(), ex.clone(), ex.clone(), GraphName::DefaultGraph);
store.insert(&quad).unwrap();

// quad filter
let results = store.quads_for_pattern(Some(ex.as_ref().into()), None, None, None).collect::<Result<Vec<Quad>,_>>().unwrap();
assert_eq!(vec![quad], results);

// SPARQL query
if let QueryResults::Solutions(mut solutions) =  store.query("SELECT ?s WHERE { ?s ?p ?o }").unwrap() {
    assert_eq!(solutions.next().unwrap().unwrap().get("s"), Some(&ex.into()));
}

It is based on these crates that can be used separately:

• oxrdf, datastructures encoding RDF basic concepts (the oxigraph::model module).
• oxrdfio, a unified parser and serializer API for RDF formats (the oxigraph::io module). It itself relies on:
  • oxttl, N-Triple, N-Quad, Turtle, TriG and N3 parsing and serialization.
  • oxrdfxml, RDF/XML parsing and serialization.
• spargebra, a SPARQL parser.
• sparesults, parsers and serializers for SPARQL result formats (the oxigraph::sparql::results module).
• sparopt, a SPARQL optimizer.
• oxsdatatypes, an implementation of some XML Schema datatypes.

To build the library locally, don't forget to clone the submodules using git clone --recursive https://github.com/oxigraph/oxigraph.git to clone the repository including submodules or git submodule update --init to add submodules to the already cloned repository.

It is possible to disable the RocksDB storage backend to only use the in-memory fallback by disabling the rocksdb default feature:

oxigraph = { version = "*", default-features = false }

This is the default behavior when compiling Oxigraph to WASM.

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.