API Reference: Subscription callback plugin
This document covers the usage of the subscription callback plugin for use in Apollo Federation with Apollo Router. For more information about the protocol itself, see the subscription callback protocol.
⚠️ Note: The subscription callback protocol is currently in preview. Breaking changes might be introduced during the preview period.
Using the plugin
This article documents the options for the ApolloServerPluginSubscriptionCallback
plugin, which you can import from @apollo/server/plugin/subscriptionCallback
.
This plugin enables your GraphQL server to respond to subscription operations using the subscription callback protocol. Apollo Router uses this protocol to execute subscription operations and receive updates at a URL specified by the router.
This feature can only be enabled by providing an ApolloServerPluginSubscriptionCallback
instance to your ApolloServer
constructor:
import { ApolloServer } from '@apollo/server';import { ApolloServerPluginSubscriptionCallback } from '@apollo/server/plugin/subscriptionCallback';const server = new ApolloServer({typeDefs,resolvers,plugins: [ApolloServerPluginSubscriptionCallback()],});
import { ApolloServer } from '@apollo/server';import { ApolloServerPluginSubscriptionCallback } from '@apollo/server/plugin/subscriptionCallback';const server = new ApolloServer({typeDefs,resolvers,plugins: [ApolloServerPluginSubscriptionCallback()],});
Caveats
The subscription plugin implementation inherently bypasses Apollo Server's request lifecycle. This means that certain plugin hooks (notably executionDidStart
and willResolveField
) will not be called when handling callback subscription requests or when sending subscription events. There is currently no metrics or tracing support for callback subscriptions.
Options
Name / Type | Description |
---|---|
| Optionally configure the heartbeat interval in milliseconds. The default is 5 seconds, which is the interval that Apollo Router expects. Lengthening this interval may cause Apollo Router to invalidate existing subscriptions frequently and is not recommended. You may want to shorten this interval if you have latency issues between your GraphQL Server and Apollo Router. |
| Optionally provide a |
| This plugin uses the The default configuration provided by this plugin is:
These defaults can be overridden (and other options can be provided) by passing an
|