How to know if an observable is successfully subscribed to a topic?

Which Category is your question related to? AWS Amplify - API Subscription Observable

What AWS Services are you utilizing? AWS Amplify, AppSync

Provide additional details e.g. code snippets I wanted to know when an observable is successfully subscribed to a specific topic. This is for the app to start triggering some actions.

Here’s what I tried thinking that complete is the callback where the observer is “now connected” or subscribed.

  subscription.subscribe({
    next: (data) => {},
    error: (error) => {},
    complete: () => {
      console.log('subscribed');
      /* emit(subscribed()); */ 
    },
  });

Unfortunately, doesn’t print out 'subscribed'.

Any thoughts?

[stocaaro]

On Monday a change was released that adds AppSync subscription connection states to Hub. With this change, it is now possible to monitor as your subscription causes the connection to transition from Disconnected -> Connecting -> Connected so that your application can know when everything is up and working.

The documentation change to cover this behavior is currently in review.

This should cover the use-case described here, I’m going to resolve the issue, but would be happy to review further if there is any aspect of this problem not covered by the Hub events.

[ume-daniel]

we run a “ping” test when we first create the subscription. we create the subscription and on a 1 second interval, send a message to that subscription with a unique id so that only we are listening to it. once we can “hear” our subscription, we disable the interval and proceed to initialize the correct subscription or do any other initialization.

NOTE: do not delete your “ping” subscription or at least wait until you subscribe to other subs as deleting the first subscription with no other’s initialized will result in the websocket closing down.