David:
Chris and Doug are the SOAP experts who have recommended the use of the
SyncReply element. I would defer to them for an explanation on the necessity
of this elemen (possibly for inclusion in the spec).
Doug stated in his last message:
http://lists.oasis-open.org/archives/ebxml-msg/200111/msg00223.html
"The previous synchronous mode would have supported MSH -> HTTP proxy -> MSH
because HTTP proxies operate in a synchronous mode by default. The new flag
allows MSH -> SOAP -> MSH in spite of the asynchronous mode the SOAP node
might prefer."
I suspect that is the main reason for the SyncReply element.
I don't quite agree with your statement "SyncReply in the MSH concerns
sending back MSHsignals." Depending on the sync reply mode set in the CPA,
SyncReply can mean returning the MSH signal synchronously, or returning the
MSH signal along with business level message (signal and/or response)
synchronously.
It also occurs to me that SyncReply may be incompatible with an AckRequested
element that is only targeted to the nextMSH. If the nextMSH returns the
intermediate Ack synchronously, how can it possibly return the application
level response also synchronously? If this observation is correct, perhaps
the incompatibility should be identified in appropriate places within the
spec.
Regards,
-Arvola