I wonder why at-least-once guarantee is easier to maintain than exactly-once (in that the latter requires 2PC while the former does not , according to http://research.microsoft.com/en-us/um/people/srikanth/netdb11/netdb11papers/netdb11-final12.pdf )
if u achieve at-least-once guarantee, you are able to assert between 2 cases "nothing" vs ">=1 delivered", which can be seen as 2 different answers 0 and 1. isn't this as hard as the common Byzantine general problem? Thanks Yang
