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Subject: RE: [ws-rx] New Issue; SequenceAcknowledgement:Final assumption ofdeliverability


If “taking responsibility” for a message implies that at least an attempt to deliver the message will be made, then I guess that the previous ack of a message with a sequence number larger than a gap is untruthful if in-order delivery is enforced.

The proposal allows the rmd to correct the previous misstatement, which it had no way of knowing was untruthful at the time it was made.  The RMS had the expectation at the previous acknowledgement that further messages may be coming which was shattered when the sequence was closed without that expectation being met.

The RMS has no way of knowing that ordered delivery was in effect, so it cannot second guess the RMD.

Alternatively, we could say that all messages that have been acknowledged will be delivered, on at least a best-efforts basis, independent of in-order delivery and the existence of gaps in the sequence.

Or, we could define durable persistence and a way for sequences to be resumed after closure (I think just too complicated)





From: Doug Davis [mailto:dug@us.ibm.com]
Sent: Wednesday, March 22, 2006 10:54 PM
To: Bob Freund-Hitachi
Cc: [WS-RX]
Subject: Re: [ws-rx] New Issue; SequenceAcknowledgement:Final assumption of deliverability


  I'm confused - doesn't the sending of an Ack for a certain message number already imply that the RMD is taking responsibility for it?  If only SeqAck+Final means that, then does that mean that a SeqAck (non-final) means something less?  like a lie?

"Bob Freund-Hitachi" <bob.freund@hitachisoftware.com>

03/22/2006 02:07 PM


"[WS-RX]" <ws-rx@lists.oasis-open.org>




[ws-rx] New Issue; SequenceAcknowledgement:Final assumption of deliverability




Modify definition of SequenceAcknowledgement:Final to reflect accurate ending delivery capability status.

The protocol defines the SequenceAcknowledgement:Final element which contains the final summary of message acknowledgements at the closure of a sequence. It is assumed that the RMD has taken responsibility for all messages that have been acknowledged.  Depending upon the operation of the RMD and its interface with the application, Messages that have been previously acknowledged as received by the RMD, may never be deliverable.  One such case of note that comes to mind is the situation of a message sequence that is being delivered in-order to an application which is closed at the time when one or more gaps that may exist in the sequence.  If this situation occurs, the RMS will have incorrect information concerning exactly which messages have been or will be deliverable at the conclusion of a sequence.

Note that there is nothing in the spec that states what the RMS is to do with the information contained in SequenceAcknowledgement:Final.  This proposal does not add any such statement, but it does permit the information to be potentially interpretable.
Target: core
Reference Core Spec CD03
insert after line 613:
SequenceAcknowledgemnt:Final shall identify only those messages that have been delivered or which the RMD has taken responsibility for delivery without regard to the previous acknowledgement status of any message.

State Table impact: None

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