Server-Consumer Communication Mode

[WalManas]

Hello,

I have a couple of questions about the Communication Mode of Server-Consumer traffic.

1. For a message that is sent from ejabberd to a consumer, with acknowledgment requested, does the server send the message asynchronously and act upon timing out, or does it block waiting for the acknowledgment from the client?
2. When a consumer recovers lets say and request offline messages, does the consumer block waiting until the call returns some data, or it is completely asynchronous process where the client will be notified once the requested data is returned?

Thanks,

Wael.