Re: [ebxml-msg] RE: [ebxml-dev] Presence of sequenceNumber elementinResponse message.

In reading section 10.1.1 of the 2.0 document, I don't see the confusion. 
The first paragraph of that section makes it rather clear the two co-operating
MSH implementations in a conversation are responsible for their own sequence
of SequenceNumber values.  I quote:
The SequenceNumber is unique within the ConversationId and
MSH. The From Party MSH 2011

and the To Party MSH each set an independent SequenceNumber as the
Sending MSH within the 2012

ConversationId. It is set to zero on the first message from that MSH
within a conversation and then 2013

incremented by one for each subsequent message sent. 2014
(Sorry for the end of line line numbers caused by Acrobat Reader.) 
What's missing?

thanx,

    doug

David Fischer wrote:
I think your question is, should SequenceNumber be
incremented at one end or at

both ends?

SequenceNumber should increment in only one (each) direction. 
Our intent was to

assure that messages sent from one business partner arrive in the right
order

rather than to sequence an entire conversation, but I don't see this
clearly

spelled out.  We may need to add a clarifying statement in the
specification.

Looking at the specification, it appears to be confusing.  If SequenceNumber
is

incremented "per conversation" which means in both directions since
a

conversation goes in both directions, there is a problem.  Suppose
CompanyA

sends to CompanyB with sequence number 1.  Then CompanyA sends
another message

to CompanyB with sequence number 2 at the same time that CompanyB sends
a reply

to CompanyA with sequence number 2.  We have two messages with
the same sequence

number.  If the sequence is per-conversation, which 2 is correct?

Am I understanding the question correctly?

I am copying the ebXML-Messaging list to solicit other comments.

Regards,

David Fischer

Drummond Group.

-----Original Message-----

From: Kumar [mailto:]

Sent: Wednesday, February 13, 2002 9:21 PM

To: David Fischer

Subject: RE: [ebxml-dev] Presence of sequenceNumber element in Response

message.

David,

My question is

wether sequence number should be incremented at the response end or
not.

Party A sends a request To Party B

with following

<MessagaeID>msg00001</MessageID>

<cpaid>cpa0001</cpaid>

<conversationid>con0001</conversationid>

<sequence>4</sequence>

Now the Party B responds to Party A

with following

<MessageID>msg00045</MessageID>

<RefToMessageID>msg00001</RefToMessageID>

<cpaid>cpa001<cpaid>

<conversationid>con0001</conversationid>

<sequence>5</sequence>

------------------------------------------------------?

here goes the doubt, in the response end wether the sequence number

element should be incremented?

wether it remains 4 or should be incremented to 5

regards

kumar

-----Original Message-----

From: David Fischer [mailto:]

Sent: Wednesday, February 13, 2002 9:50 PM

To: Kumar; 

Subject: RE: [ebxml-dev] Presence of sequenceNumber element in Response

message.

In both v1.0 and v2.0, ConversationId is a required element on all

messages.

Neither version specifies what its value must be other than it must
be

unique

between the too parties.  The concept is of grouping messages
which

pertain to

the same thread using this element.  How this is done is not specified

(implementation dependent) and is not used within the confines of the

MSH, with

one exception.

Message Ordering -- SequenceNumber (when present) -- is used within
a

Conversation.  ConversationId does not contain (is not an ancestor
of)

SequenceNumber.  This is the only time ConversationId is specifically

used in

the specification.  SequenceNumber is not a required element on
any

message.

The CPA specifies whether or not SequenceNumber should be present. 
If

it is

present, it is incremented within a single Conversation.  A

SequenceNumber of

*1* on two different messages with different ConversationId values
is a

valid

construct.  A SequenceNumber of *1* on two different messages
with the

same

ConversationId value, is not a valid construct, unless a Reset is

performed

between the messages.

Regards,

David Fischer

Drummond Group.

-----Original Message-----

From: Kumar [mailto:]

Sent: Tuesday, February 12, 2002 11:39 PM

To: 

Subject: [ebxml-dev] Presence of sequenceNumber element in Response

message.

Hi! ebXML folks,

According to ebXML TRP spec "1.0" if the message is reliably sent,
it

Must contain the Conversationid element which in turn has a sequence

Number element.

Consider a Situation where two Parties are exchanging some services,

example Party A and Party B

If Party A  initiates the conversation ,

then in the request message following elements appear

MessageID

ConversationID

SequenceNumber

Now the

Party B responds to Party A  , while responding wether the Sequence

Number element must be present or not. If present wether it can be

incremented on the response end.

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