Re: SequenceNumber [was:minutes 21-Dec-2000 tr&p con-call]

[Nikola Stojanovic <nhomest1@twcny.rr.com>]

<SHIMAMURA Masayoshi>
...
I think message order is represented by MessageId and RefToMessageId as
following in your idea:
      1st Message [MessageId = a]
      2nd Message [MessageId = b, RefToMessageId = a]
      3rd Message [MessageId = c, RefToMessageId = b]
      4th Message [MessageId = d, RefToMessageId = c]

I don't think it is good idea. Please consider following case:
  The 1st Message includes main business payload. Other Messages (2nd to
  4th) includes addendum business payload to 1st Message's main business
  payload. At same time, the order of business payloads has a meaning in
  business. This is widely used business document structure (ex. license
  agreement). If all the messages have SequenceNumber, the structure can
  be represented correctly as following:
      1st Message [MessageId = a, SequenceNumber = 1]
      2nd Message [MessageId = b, RefToMessageId = a, SequenceNumber = 2]
      3rd Message [MessageId = c, RefToMessageId = a, SequenceNumber = 3]
      4th Message [MessageId = d, RefToMessageId = a, SequenceNumber = 4]

If you use MessageId and RefToMessageId instead of SequenceNumber, you can
not handle the structure above.
</SHIMAMURA Masayoshi>

I cannot see why. Also, it seems to me that using the first example one can
have something like this:

      1st Message [MessageId = a]
      2nd Message [MessageId = b, RefToMessageId = a]
      3rd Message [MessageId = c, RefToMessageId = a]
      4th Message [MessageId = d, RefToMessageId = b]
      5th Message [MessageId = e, RefToMessageId = c]

and I cannot see how SequenceNumber example can handle that.

But, maybe this is just speculating about requirements that don't exist (it
would take me a while to find a Use Case delivery matrix) for Phase 1.
AFAIR, SequenceNumber was introduced in order to do Reliable Messaging and
Temporal Ordering of messages wasn't part of it.

Regards,
Nikola