RE: [ws-rx] i066:Proposal to remove LastMessage, but retain LastMessage

Bob:

In a LastMessage-less scenario, If RMS got all the acks it was waiting for (having knowledge of what was last message it sent for this sequence) it has no need to close the sequence: it can terminate it directly.

Bottom line is: "someone" (either RMS or RMD) will have to wait for all messages to have been received (or wait for a confirmation of this) to take action for reclaiming resources on RMD side.

- With LastMessage, RMD has to remember.

- Without LastMessage, RMS has to remember.

Sure there is a final additional TerminateSequence to be sent in second case, but that small overhead is to balance with the increased complexity of the protocol in first case.

Note that this overhead in the sequence termination protocol disappears in case the AS happens to knows it was its last message - or cares to signal this to RMS - only *after* having sent it, (as opposed to at the time that last message is being sent) which I expect to be by far the most common case. Indeed in that case, an empty additional message with LM will have to be sent.

Jacques

From: Doug Davis [mailto:dug@us.ibm.com]
Sent: Wednesday, November 30, 2005 10:58 PM
To: ws-rx@lists.oasis-open.org
Subject: Re: [ws-rx] i066:Proposal to remove LastMessage, but retain LastMessage functionality

"Bob Freund-Hitachi" <bob.freund@hitachisoftware.com> wrote on 11/30/2005 08:19:14 PM:
> The issue 66 requires the the RMS to wait for receipt of all of the
> Acks before issuing CloseSequence to safely close the sequence.
> However, LastMessage does not require the RMS to do so.
> The reason is that LastMessage contains a message number while
> CloseSequence does not.
> If we were to add an optional last message number element to the
> CloseSequence message the functionality of LastMessage would be
> preserved should LastMessage be determined to be superfluous.

I'm assuming you want to add a lastMessage to Close is so that the RMD
will still allow lower numbered messages in - if so then that defeats
the purpose of Close since its intention is to prevent ANY new messages
from being delivered - in otherwords, the RMS is ok with the gaps that
may exist in the sequence.
thanks,
-Doug

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