Adding Mqttv5PahoMessageDrivenChannelAdapter to running Mqttv5ClientManager

[Ricore72]

version 6.3.1

Description
I want to add multiple instances of Mqttv5PahoMessageDrivenChannelAdapter (on demand, when application is running) using already running client in Mqttv5ClientManager as constructor parameter. When I try, it does not work.
Cause seams to be MqttCallback:: connectComplete ,which sets the readyToSubscribeOnStart property.
That obviously cant trigger because client is already connected.

To Reproduce

1. Create an instance of Mqttv5ClientManager
2. Start clientManager
3. create an instance of Mqttv5PahoMessageDrivenChannelAdapter with clientManager
4. register adapter in IntegrationFlow using IntegrationFlowContext
5. Try to send messages to it

Possible Fix
https://github.com/Ricore72/spring-integration
The fix does not work completely.

It only works if Handlers and adapters using same clientManager have the same Qos.

Note
I am not sure if this is the proper way to do this. This is my first issue to public project. So sorry if it is incorrect in any way.

[artembilan]

It looks like the ClientManager should expose an isConnection() API.
The problem is that your ClientManager has been started and connected.
So, all those dynamically added channel adapters at runtime just lose their connectComplete() callback.
Therefore in the AbstractMqttMessageDrivenChannelAdapter.onInit() we should check for the mentioned ClientManager.isConnection() and set readyToSubscribeOnStart = true.
So, when this dynamic channel adapter is started it will understand that it is already OK to subscribe.

Feel free to play with that and contribute back: https://github.com/spring-projects/spring-integration/blob/main/CONTRIBUTING.adoc

Thank you!

[artembilan]

I changing this to Enhancement since we never advertised that such a scenario is supposed to work.
So, new feature for new version.
Will review your PR shortly.
Thanks