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Subject: Re: [ebxml-msg] Issue for your review
My apologies. ;-) s/transport/transfer/g thanx, doug Doug Bunting wrote: > Dave, > > An excellent description of how very little we say in the Messaging > specification can completely control the observed ordering of responses seen at > the originating server. Your example describes a real world issue resulting > from a clear separation of concerns between the ebXML and transport layers. > > The other case I was attempting to describe earlier involved separating concerns > between the application and ebXML layers. I had misread or forgotten the > original issue description and thought we were discussing a SyncReply / > syncReplyMode="mshSignalsOnly" / AckRequested case. What I was describing in an > earlier email is an indeterminate ordering of business and MSH signals or > responses in this case. The MSH MUST make the incoming message available to the > application prior to returning (via the HTTP 200 reply if using that transfer > protocol) an Acknowledgment message. The MSH has no control over how quickly > the application operates so business signals or responses may arrive at the > originating server before the Acknowledgement message. We could try to force > that MSH to prevent outgoing messages including a RefToMessageID pointing to the > one it's working on but we can't guarantee the same MSH will even be used for > the outgoing message or close all of the race conditions. And, so... > > In both cases, we need to describe the issue so originating servers do not > depend upon particular orderings rather than increasing the complexity of the > receiving server to (slightly) lessen the chances for ordering to follow > less-than-obvious patterns. > > thanx, > doug > > Dave Elliot wrote: > ... > > > Here's another real world problem. Suppose the Responder behaves as you > > suggest and does not send an async EbXML Ack until the transport layer > > of the inbound message has wrapped up. So in effect you have this > > sequence: The Responder sends HTTP 202 and then immediately sends the > > EbXML Ack over a different DeliveryChannel (possibily different > > transport protocol). > > > > Now let us suppose that the EbXML Ack delivery protocol is faster to > > send and to unmarshall/process than HTTP. This means that the ebXML Ack > > would arrive up at the Sender's EbXML Layer before the Sender's HTTP > > transport was able to confirm to its EbXML Layer that the original > > message was even sent. > > > > Which illustrates that even if you were to mandate the transport/ebXML > > layer sequence that the Responder must follow, the sequence may still > > occasionally/randomly appear different to the Requester. That's why I > > don't think it is safe to mandate that kind of thing. > > > > Best Regards, > > > > Dave Elliot > > XML Global Technologies > > > > ---------------------------------------------------------------- > > To subscribe or unsubscribe from this elist use the subscription > > manager: <http://lists.oasis-open.org/ob/adm.pl> > > ---------------------------------------------------------------- > To subscribe or unsubscribe from this elist use the subscription > manager: <http://lists.oasis-open.org/ob/adm.pl>
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