WebSocket connection close on reconnect

[paparent]

Describe the bug

AWS IoT Core limits each SUBSCRIBE packet to a maximum of 8 topics.

When a connection is lost in the browser, on reconnect with clean session turned on, it subscribes to every topics at once.

The MQTT.js now support batching since version 5.13.0: mqttjs/MQTT.js#1995

Expected Behavior

On reconnect, subscribe to topic in batch of 8 maximum.

Current Behavior

On reconnect, it subscribe to all topics.

Reproduction Steps

Subscribe to more than 8 topics.

Trigger a WebSocket failure. You can queryObjects(WebSocket), find the object and call .close() on it.

Possible Solution

No response

Additional Information/Context

No response

SDK version used

1.23.0

Environment details (OS name and version, etc.)

Browser

[sbSteveK]

We are currently using mqtt.js 4.3.8 and have been unable to migrate to mqtt 5+ due to breaking changes and bugs that have not yet been addressed. We have made requests to the maintainers of mqtt.js and are exploring alternate avenues.

In the meanwhile, we suggest handling reconnection and resubscribing manually upon a disconnect and reconnect.

[paparent]

@sbSteveK thank you for your reply. I'd need help to implement your suggestion. The resubscribe option sent to the mqttjs client can't be overridden, so I can't set it to false. I've looked at this library and aws-crt and I can't seem to find a way to stop doing re-connection and resubscribe is a loop (like the v1 of this library did via autoResubscribe).

[bretambrose]

For now, we can add a flag to disable resubscribe. The client config for browser and node are already different so it's not really disruptive. We hope to have a solution for the larger problem (upgrading mqtt-js) in a few months.