Serve RDF with content negotiation

This guide shows how to serve RDF from a Fastify app in whatever serialisation the client asks for, using @lde/fastify-rdf.

Register the plugin

Install the plugin alongside Fastify:

npm install @lde/fastify-rdf

Then register it on your app:

import fastify from 'fastify';
import fastifyRdf from '@lde/fastify-rdf';

const app = fastify();
await app.register(fastifyRdf);

Serve RDF from a route

Return reply.sendRdf() with an RDF/JS dataset (such as an N3 Store) or quad stream. The plugin serialises it in the format the Accept header requests:

import { DataFactory, Store } from 'n3';

const { namedNode, literal, quad } = DataFactory;

app.get('/resource', async (request, reply) => {
  const store = new Store();
  store.add(
    quad(
      namedNode('http://example.org/subject'),
      namedNode('http://example.org/predicate'),
      literal('object'),
    ),
  );
  return reply.sendRdf(store);
});

Clients pick the format; without an Accept header (or with */*) the response is Turtle:

curl -H "Accept: application/n-triples" http://localhost:3000/resource

curl http://localhost:3000/resource # Turtle

See the @lde/fastify-rdf reference for the supported formats and the remaining options: automatic serialisation of every response (overrideSend), parsing RDF request bodies (parseRdf), Hydra error responses (reply.sendHydraError()) and changing the default content type.