Marty:
I tend to agree with you that RosettaNet is not a use case that demonstrates
the need for message ordering in the MSH.
A BPSS BusinessTransaction has an "isGuaranteedDeliveryRequired" attribute.
We interpret "isGuaranteedDeliveryRequired" set to true to mean that
Reliable Messaging is to be used. If Reliable Messaging guarantees delivery
order, it allows process designers to take advantage of the message ordering
and optimize away the use of Receipt Acknowledgment signals (when there is
no non repudiation of receipt requirement.
I am in favor of the CPA stating whether the use of Reliable Messaging
between two parties also implies that messaging ordering to be supported for
every conversation. I don't think we should allow message ordering to be
enabled for just a subset of the messages within a conversation. In other
words, I don't think the decision to include a MessageOrder element should
be a "per message" decision. It should be completely determined by the CPA.
The sole purpose of the MessageOrder element is to carry the sequenceNumber.
I agree with Doug that the messageOrderSemantics within MessageOrder (in the
Messaging Service schema) should be done away with, and that the
SequenceNumber should always be required.
Regards,
-Arvola