RE: minutes 21-Dec-2000 tr&p con-call

[Doug Bunting <Doug@ariba.com>]

Again, this is a relatively low-level issue we might tackle if and when we
decide that in-order delivery is something the MSH should guarantee.
Duplicate detection is already well covered by the MSH specification.

Unfortunately, your description doesn't help with the issue I intended to
raise.  I was speaking about your proposed modification (thinking it was
"current"), which added a Reset condition.

Say the sender sent messages 99, 100 and 101, then reset the sequence number
series.  The receiver MSH may receive messages 99, 100 and 0 and think
that's correct for in-order delivery to the application layers.  The sender
may be retrying message 101 at about the same time.  But, it doesn't help
matters now that the messages have been passed "up".

thanx,
	doug

-----Original Message-----
From: SHIMAMURA Masayoshi [mailto:shima.masa@jp.fujitsu.com]
Sent: December 28, 2000 23:25
To: Doug Bunting
Cc: 'Burdett, David'; ebXML Transport (E-mail); IWASA Kazunori; Jacques
Durand
Subject: Re: minutes 21-Dec-2000 tr&p con-call

Mr. Doug Bunting, 

On Wed, 27 Dec 2000 15:59:44 -0800
Doug Bunting <Doug@ariba.com> wrote:
...
> Lower-level issues with the current sequence number semantics: The
> wraparound algorithm does not guarantee delivery of the last few messages
> before starting at 0.  The receiver has no way to learn what the highest
> number was prior to wrapping around.  And, how do these semantics handle
> messages that fail due to an incorrect ebXML Header document?  Should a
> replacement message that corrects the error reuse the previous sequence
> number?

To resolve the problem you pointed out, WindowSize has following
limitation:

    maximum WindowSize <= range size of SequenceNumber / 2

It is not my original idea, it is usual way in SlidingWindow algorithm.
In the latest RM spec, range size of SequenceNumber is 100,000,000 (0 -
99,999,999). So maximum WindowSize is 50,000,000. I will revise the
description of the WindowSize to add this. Thank you for your mention.


Regards, 

--
SHIMAMURA Masayoshi <shima.masa@jp.fujitsu.com>
TEL:+81-45-476-4590(ext.7128-4241)  FAX:+81-45-476-4726(ext.7128-6783)
Planning Dep., Strategic Planning Div., Software Group, FUJITSU LIMITED