On 09/19/2012 09:28 AM, Zhemzhitsky Sergey wrote:
Hi Gordon,
Thanks for the answer.
I'm wondering whether there is any possibility to move the prefetch window only
after a message or a number of messages are acknowledged?
It isn't supported now. Can you elaborate a little on the use cases for
that behaviour?
There are two questions in my mind. The first is simply how to allow
users to specify they want that behaviour in a neat and simple way. The
second is more problematic.
At present for capacity > 1 I use the AMQP 0-10 'window' mode for
credit, where the window is moved by session-completed controls. However
messages are considered completed as soon as they are received by the
messaging library. All that is then needed is to periodically send
information about the completed messages.
However, in this scheme, other actions on the session can result in that
completion information being sent to the broker (which would move the
window forward).
To give a guarantee that the 'prefetch' window moved only when messages
are acknowledged (not just fetched), I would need to change to use
explicit credits. I haven't thought it through in detail but if that
turned out to be a large amount of work, I'd probably argue for dealing
with it only on the 1.0 implementation.
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