Ack only after processing

This may be nitpicking, but IMHO we should only ack the message after all postprocessing was done.
I understand that this is arguable, since currently we ack after we saved the raw data. I just feel this to be more correct, even if we do not check the success of the postprocessing. Ideally we should wrap both in a transaction and only ack on successful commit.

Feel free to close this if you don't agree.