Subscriptions are GraphQL operations that watch events emitted from your backend. GraphQL Modules supports GraphQL subscriptions with a little modification in your server code. You can read more about SubscriptionServer.
Subscriptions need to have defined
PubSub implementation in your GraphQL Modules application.
You have to export
subscriptions from your
AppModule, and pass it to your GraphQL Server.
Session life-time when using WebSocket is the same as the connection's. So, you can keep all the user state in your memory.