Hey@acogoluegnes!

Here's a proposal for implementing "automatic" publisher confirmation tracking in a similar manner to the .NET client. As you're the expert here, please suggest better names, a better implementation, etc, as I'm just barely familiar enough with Java and this project to implement this feature with the help of a genie. I did, of course, review the code.

If you like the way this is going, I thought I'd also add rate-throttling in a similar manner to the .NET client, i.e. as the outstanding confirmation window closes, increase delay between publishes to (hopefully) allow the broker to catch up.

Thanks for this contributon@lukebakken. I think it is on the right track. I added some comments in the code. Just a few more remarks:

• the new methods in the public interfaces should have a default implementation if we back port the PR to 5.x. This is for backward compatibility. Throwing an exception is good enough.
• synchronized blocks and Object-based synchronization is considered old-style Java concurrency. We could see if there are more modern utilities in the Java concurrency toolkit to handle what we need inChannelN. I'm not super opinionated on this topic though and this is an implementation details we can polish later.
• the bulk of the PR is inChannelN, it is not rocket science but add some non-trivial logic to a somewhat already complex class. I was wondering if it could be possible to externalize all the logic in aPublishConfirmState class used fromChannelN. This state class would register regular return and confirm listeners on the channel. This could even be an interface with a no-op implementation when the feature is not activated, minimalizing the impact onChannelN. We can discuss this design when all the features are added.

@lukebakken I have sent you an external contributor invite for this repo.

@michaelklishin@acogoluegnes I tookthis comment to heart and re-implemented this feature as aConfirmationChannel class that wrapsChannelN and does its own confirmation tracking. That way, no modifications to the existingChannel interface orChannelN class are necessary.

Alrighty gang, all set I think. Small tutorial here -rabbitmq/rabbitmq-tutorials#707

@lukebakken since this is a feature by most definitions, we now would have to go through a special approval process on our end :(