Subscriptions Link

Execute subscriptions (or other operations) over WebSocket with the graphql-ws library

We recommend reading

Apollo Link overview

before learning about individual links.

The GraphQLWsLink is a

terminating link

that's used most commonly with GraphQL

subscriptions

(which usually communicate over WebSocket), although you can send queries and mutations over WebSocket as well.

GraphQLWsLink requires the

graphql-ws

library. Install it in your project like so:

1
npm install graphql-ws

Note: This link works with the newer graphql-ws library. If your server uses the older subscriptions-transport-ws, you should use the

WebSocketLink link from @apollo/client/link/ws

instead.

Constructor

1
import { GraphQLWsLink } from "@apollo/client/link/subscriptions";
2
import { createClient } from "graphql-ws";
3

4
const link = new GraphQLWsLink(
5
  createClient({
6
    url: "ws://localhost:3000/subscriptions",
7
  }),
8
);

Options

The GraphQLWsLink constructor takes a single argument, which is a Client returned from the graphql-ws createClient function.

The createClient function can take many options, described in the

graphql-ws docs for ClientOptions

. The one required option is url, which is the URL (typically starting with ws:// or wss://, which are the equivalents of http:// and https:// respectively) to your WebSocket server. (Note that this differs from the

older link's URL option

, which is named uri instead of url.)

Usage

See

Subscriptions

Schema

WebSocket (older protocol)