A comment with respect to state alignment and work unit. It looks like
the granularity at which isAligned() can be used is too big and that
could defeat the purpose of work units along with state alignment which
are otherwise very useful concepts. BPSS offers alignment at the message
level (it is not because you received a message that this message is
understood as valid and can be processed by the receiver). If no
protocol is available to notify the sender of potential standard errors
for each message, then these error notifications must be implemented in
the choreography itself. This is not a satisfying solution, because you
end up acking the ack. As I learned it, it is only through the use of
widely agreed upon and structurally constant signals that you can really
guarantee state alignment otherwise, I am under the impression that it
will remain a wish rather than a fact.