fix(@aws-amplify/pubsub): Handle onclose events in AwsRealTimeSocket

[greimela]

Issue #, if available:
#5403

Description of changes:
This change allows a user of the socket to restart the subscription after it terminates without an error.
This can sometimes happen when devices enter or leave standby.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

Merging #6448 into main will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main    #6448      +/-   ##
==========================================
- Coverage   73.31%   73.29%   -0.02%     
==========================================
  Files         208      208              
  Lines       12922    12925       +3     
  Branches     2526     2526              
==========================================
  Hits         9474     9474              
- Misses       3257     3260       +3     
  Partials      191      191              

Impacted Files	Coverage Δ
...pubsub/src/Providers/AWSAppSyncRealTimeProvider.ts	18.37% <0.00%> (-0.17%)	⬇️

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[bensie]

We're seeing the same behavior as described in #5403 and would love to see this merged!

[ericclemmons]

@greimela @bensie I was able to validate this (including @adamup928's example from #5403).

Since a socket reconnect doesn't happen automatically, how are/would you handling reconnecting?

[ericclemmons]

Thanks for this PR!

I confirmed I can pick up on the close event via the error method:

const subscription = API.graphql({
      authMode: owner ? 'AMAZON_COGNITO_USER_POOLS' : 'AWS_IAM',
      query: onUpdateAlbum,
      variables: { owner },
    }).subscribe({
      error(error) {
        console.log('Subscription error', error);
      },
      next(payload) {
        setAlbum(payload.value.data.onUpdateAlbum);
      },
    });

[greimela]

@ericclemmons Nice, thanks for the confirmation!

We are using the error callback to restart our subscriptions. So if the close events arrive there it's perfect for us 👌

[elorzafe]

Thanks @greimela 🎉 🌮 🥇

[bensie]

@greimela Would you mind sharing how you trigger the websocket reconnect from within the subscribe error function? It doesn't seem like triggering resubscribes causes the websocket connection to reconnect if it's no longer active. Thanks!

[greimela]

@bensie We are actually opening a completely new subscription in the case of an error.

[bensie]

@greimela Guessing I'm missing a step here and I think we might be mixing up terminology - with 1 websocket connection and many subscriptions on that connection, if the websocket connection is closed and the onclose event is fired, how do you reconnect the websocket ahead of re-initiating those subscriptions? Do you have a code snippet you could share?

[greimela]

@bensie We are using this lib only through the GraphQL subscriptions, so we might speak of different subscriptions here.

We just call API.graphql(...).subscribe(...) again after we get the error.

[bensie]

@greimela Interesting, thanks! I'll keep digging, when we do that the websocket connection doesn't seem to reconnect automatically and the resubscribe fails.

[github-actions]

This pull request has been automatically locked since there hasn't been any recent activity after it was closed. Please open a new issue for related bugs.

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