WebSocket Link

⚠️ We no longer recommend using WebSocketLink or the subscriptions-transport-ws library, because the library is not actively maintained. To execute subscriptions, We instead recommend using the newer graphql-ws library with the accompanying GraphQLWsLink.

Whichever library you use, make sure you use the same library in your server and any clients you support. For more information, see Choosing a subscription library.

We recommend reading Apollo Link overview before learning about individual links.

The WebSocketLink 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.

WebSocketLink requires the subscriptions-transport-ws library. Install it in your project like so:

1npm install subscriptions-transport-ws

Constructor

1import { WebSocketLink } from "@apollo/client/link/ws";
2import { SubscriptionClient } from "subscriptions-transport-ws";
3
4const link = new WebSocketLink(
5  new SubscriptionClient("ws://localhost:4000/graphql", {
6    reconnect: true
7  })
8);

Options

The WebSocketLink constructor takes either a SubscriptionClient object or an options object with the following fields. (These options are passed directly to the SubscriptionClient constructor.)

uri

String

Required. The URL of the WebSocket endpoint to connect to (e.g., ws://localhost:4000/subscriptions).

options

Object

Options for configuring the WebSocket connection.

See supported options

webSocketImpl

Object

A W3C-compliant WebSocket implementation to use. Provide this if your environment does not provide native WebSocket support (for example, in Node.js).

Usage

See Subscriptions.