Message Ordering Use Cases

["Pim van der Eijk" <pim.vandereijk@oasis-open.org>]

 

I took an action item to provide some use cases for message ordering.  Here are two (generalized/anonymyzed from some practical cases)

 

1) A simple one is a status change event notification. 

Parter_A monitors some entity or system of interest and notifies Partner_B of any changes. B wants to know the latest status of the observed entity and also wants to have a historical overview of all changes.

Sometimes there are no changes for days, but when there are changes it is possible that one change is very short, perhaps as short as seconds, after the other.

Reliable messaging is important as B wants to get all changes.

Ordering is important so that B has no misunderstanding about what is the latest status.

 

2) A slightly more complex example

Partner A is a front-end organization for Partner B, handling customer service issues.

Issues are communicated by A to B using a "Create Issue" message.  This is the first message in a conversation. The message handler sets the value for ConversationId by selecting the value of an XML element called IssueId from the XML payload.  This value is reused by any subsequent messages about the issue, to allow monitoring.

 

Subsequent "Update Issue" messages can be sent by A to B to provide updated information. Since a later update may reference earlier ones, they need to be processed sequentially. The first "Update Issue" must be processed after the "Create Issue" message.  Sequence membership can be determined based on ConversationId (and AgreementRef).

 

A "Close Issue" message may also be sent by A to B when the customer indicates the problem has been solved. This message has the same ConversationId as the "Create Issue" and "Update Issue" messages.  It needs to be processed after the "Create Issue" message. However, a "Create Issue" message needs to be processed as soon as possible, and if there are any "Update Issue" messages that have not yet been processed, they can be ignored.

 

 

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