[ebxml-msg] MessageOrder element usage

[SHIMAMURA Masayoshi <shima.masa@jp.fujitsu.com>]

ebMS TC members, 

I'd like to raise an issue about MessageOrder element usage. Section
9.1.1 of the specification says:

    9.1.1 SequenceNumber Element
    ... The From Party MSH and the To Party MSH each set an independent
    SequenceNumber as the Sending MSH within the ConversationId. ...
  
The description seems to me that Acknowledgment Message should have
SequenceNumber as follows:

    From Party MSH                            To Party MSH
        ------ Message with SequenceNumber 1 ---->
        <----- Ack Message with SeqeunceNumber 5--

        ------ Message with SequenceNumber 2 ---->
        <----- Ack Message with SeqeunceNumber 6--
                             .
                             .

But actually the SeqeunceNumber on Acknowledgment Message is unnecessary.
Because SeqeunceNumber is not used on From Party MSH, it is used on only
To Party MSH as description in Section 9:

    9. MessageOrder Module
    The MessageOrder module allows messages to be presented to the To
                                                                   ~~
    Party in a particular order. This is accomplished through the use of
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~
    the MessageOrder element. Reliable Messaging MUST be used when a
    MessageOrder element is present. MessageOrder module MUST only be
    used in conjunction with the ebXML Reliable Messaging Module
    (section 6) with a scheme of Once-And-Only-Once (sections 6.6). If a
    sequence is sent and one message fails to arrive at the To Party MSH,
                                                            ~~~~~~~~~~~~~
    all subsequent messages will also fail to be presented to the To
                                                                  ~~
    Party Application (see status attribute section 9.1.1).
    ~~~~~~~~~~~~~~~~~

I guess that the description in 9.1.1 is the result of a consideration
to guarantee message order on SyncReply mode. But current specification
does not accept using SyncReply and MessageOrder at same time:

    9.2 MessageOrder Element Interaction
    For this version of the ebXML Messaging Specification, the
    MessageOrder element MUST NOT be present with the SyncReply element.
    If these two elements are received in the same message, the
    Receiving MSH SHOULD report an error (see section 4.1.5) with
    errorCode set to Inconsistent and severity set to Error.

So I recommend that the description in 9.1.1 should be changed as
follows:

    9.1.1 SequenceNumber Element
    ... The From Party MSH set an SequenceNumber as the Sending MSH
    within the ConversationId. ...


Regards, 

--
SHIMAMURA Masayoshi <shima.masa@jp.fujitsu.com>
TEL:+81-45-476-4590(ext.7128-4241)  FAX:+81-45-476-4749(ext.7128-6780)
Strategy Planning Dep., Strategy and Technology Div., Software Group, 
FUJITSU LIMITED


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