Re: [ebxml-msg] Comments on the 1.09 about MessageOrder

[Doug Bunting <dougb62@yahoo.com>]

I think this change would disallow using the Message Order feature with an
underlying reliable communications protocol.  Duplicate elimination is
necessary at the MSH level regardless of the reliability of the
communications protocol because that protocol can't know what duplicates
"matter".  However, retries ensuring the message got to the destination can
be done below the MSH level.

The problem with this change is really our convention Once-and-Only-Once
means the MSH level is doing everything.  If we made it more clear this
could include reliable communication protocols to get to the same
reliability, I'd be fine with this change.

thanx,
    doug

----- Original Message -----
From: "SHIMAMURA Masayoshi" <shima.masa@jp.fujitsu.com>
To: <ebxml-msg@lists.oasis-open.org>
Sent: Thursday, 29 November 2001 01:25
Subject: [ebxml-msg] Comments on the 1.09 about MessageOrder


Please change section 10 as following:

  P. 49, Line 1993-1994.
    It is highly RECOMMENDED that Reliable Messaging be used when a
    MessageOrder element is present.
      |
      V
    Reliable Messaging MUST be used when a MessageOrder element is
    present.

  P. 49, Line 1997.
    SHOULD
      |
      V
    MUST

  P. 49, Line 2009.
    The MessageOrder element MUST be used with the duplicateElimination
    attribute set to true.
      |
      V
    The MessageOrder element MUST be used with delivery behavior of
    Once-and-Only-Once. The Once-and-Only-Once delivery behavior means
    that duplicateElimination set to true and AckRequested element
    appears in messages, or duplicateElimination set to true and
    Acknowledgement element appears in messages.

  P. 49, Line 2021.
    only when duplicateElimination is true.
      |
      V
    only when delivery behavior is Once-and-Only-Once.

  P. 49, Line 2023.
    If duplicateElimination is not true
      |
      V
    If delivery behavior is not Once-and-Only-Once

  P. 49, 2025-2026
    that have a duplicateElimination attribute with a value of true
      |
      V
    that have delivery behavior is Once-and-Only-Once

  P. 50, Line 2044 and 2046.
    when duplicateElimination has a value of true
      |
      V
    when delivery behavior is Once-and-Only-Once

  P. 50, Line 2050 and 2052.
    When duplicateElimination is true
      |
      V
    When delivery behavior is Once-and-Only-Once


Because guarantee of message order can be realized only when delivery
behavior is Once-and-Only-Once. Actually in the Message Service
specification V1.0, guarantee of message order can be specified only
when delivery behavior is Once-and-Only-Once.

Please consider following case:

    MessageOrderSemantics: Guarantee
    Delivery behavior: At-Most-Once (duplicateElimination is true and
                                     AckRequired is not used).

                            +----------+
    ---- Message (SN=1)---> |receiving |
    ---- Message (SN=2)---> |    MSH   |
    ---- Message (SN=4)---> |          |
                            +----------+

In this case, receiving MSH is not sure that the Message of SN 3
will reach after that. It might never reach forever. It means that
receiving MSH can't decide that when the Message of SN 4 should be
passed to application.


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


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