[ebxml-dev] ConversationId Ambiguity

[kumar <kumar@SAMSUNGSDSINDIA.com>]

Hi! ebXML folks,

Specification says the ConversationId Must be unique between From and To
Party pair.

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The REQUIRED ConversationId element is a string identifying the set of
related messages that make up a conversation between two Parties. It
MUST be unique within the From and To party pair.  The Party initiating
a conversation determines the value of the ConversationId element that
SHALL be reflected in all messages pertaining to that conversation.
The ConversationId enables the recipient of a message to identify the
instance of an application or process that generated or handled earlier
messages within a conversation. It remains constant for all messages
within a conversation.


All messages sent within the same conversation, as identified by the
ConversationId element, that have a deliverySemantics attribute with a
value of OnceandOnlyOnce SHALL each have the same value
messageOrderSemantics (either Guaranteed or NotGuaranteed).

SequenceNumber element
The SequenceNumber element indicates the sequence in which messages MUST
be processed by a Receiving MSH. The SequenceNumber is unique within the
ConversationId and MSH.  The From Party MSH and the To Party MSH each
set an independent SequenceNumber as the Sending MSH within the
ConversationID.  It is set to zero on the first message from that MSH
for a conversation and then incremented by one for each subsequent
message sent.
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When you carefully scan the specification, Initially it says that
ConversationId Must be unique within From and To Party pair. Again it
says that it remains constant within in 
within a conversation.And again it says that Sequence Number is unique
within the conversationId and MSH.
Now the question wether the ConversationId is Unique within From and To
Party pair?
wether the ConversationId remains same for the set of messageIds?
If ConversationId is unique and changes with each messageId then what is
the essence of sequence number?


Regards
kumar