graphql-ws

What is graphql-ws?

The graphql-ws package is a lightweight and fast WebSocket server and client for GraphQL subscriptions, designed to work with the GraphQL JavaScript reference implementation. It allows you to set up a full-duplex communication channel between the client and server to facilitate real-time data exchange using the GraphQL protocol.

What are graphql-ws's main functionalities?

Creating a WebSocket server for GraphQL subscriptions

This code sample demonstrates how to create a WebSocket server that handles GraphQL subscriptions. It uses the `useServer` function from `graphql-ws` to attach the WebSocket server to an existing HTTP server.

const { createServer } = require('http');
const { execute, subscribe } = require('graphql');
const { useServer } = require('graphql-ws/lib/use/ws');
const { schema } = require('./my-graphql-schema');

const server = createServer(function weServeSocketsOnly(_, res) {
  res.writeHead(404);
  res.end();
});

const wsServer = new WebSocket.Server({
  server,
  path: '/graphql',
});

useServer({ schema, execute, subscribe }, wsServer);

server.listen(4000);

Creating a WebSocket client for GraphQL subscriptions

This code sample shows how to create a WebSocket client that can subscribe to GraphQL subscriptions. The `createClient` function from `graphql-ws` is used to establish a connection to the WebSocket server, and the `subscribe` method is used to listen for real-time data updates.

const { createClient } = require('graphql-ws');

const client = createClient({
  url: 'ws://localhost:4000/graphql',
});

client.subscribe(
  {
    query: 'subscription { somethingChanged { id } }',
    variables: {},
  },
  {
    next: data => console.log('data received:', data),
    error: err => console.error('error during subscription:', err),
    complete: () => console.log('subscription completed'),
  }
);

Other packages similar to graphql-ws

subscriptions-transport-ws

This package is another implementation of GraphQL over WebSocket protocol. It is the predecessor of graphql-ws and was developed by the Apollo team. However, it is now deprecated in favor of graphql-ws, which is more lightweight and has a simpler API.

apollo-server

Apollo Server is a community-driven, open-source GraphQL server that works with many Node.js HTTP server frameworks. Apollo Server supports subscriptions with WebSocket and integrates well with the Apollo ecosystem. It is more feature-rich but also heavier compared to graphql-ws, which is focused solely on WebSocket communication.