RE: Correlation Requirements

Monica

The reason I included requirements 2 and 3 is that they reflect two use
cases ...

If we assume that there has to be some data in the message that can be used
for correlation when the message is taking part in a choreography then
requirement 2 arises becaus it is possible that there is no data in the
payload (or anywhere else) that can be used for correlation purposes.

Requirement 3 arises because there maybe data that can be used in the
payload and therefore you don't want to have to be forced to use an
identifier in the header.

However, I can also see your point that the existing requirement definitions
could be a bit too presrcriptive, so how about these as alternatives, I've
added a fourth requirement which hopefully makes it clearer. The complete
set is as follows ...

Requirement 1 (not changed)
If a message is being sent between roles as part of the "performance" of a
choreography, then that message MUST identify the "choreography instance" to
which it belongs.

Requirement 2 (changed)
A choreography instance MUST be identified by specifying a separate
identifier associated with the payloads in the message where there is no
combination of data in the "payload(s)" that can be used to uniquely
identify the choreography instance that is being performed.

Requirement 3 (changed)
A choreography instance MAY be identified by referencing a combination of
one or more items of data in the "payload(s)" of the message where that
combination of data can be used to uniquely identify the choreography
instance that is being performed.

Requirement 4 (new)
A choreography  instance MAY be identified by specifying a separate
identifier associated with payload(s) in the message even if there is a
combination of data in the "payload(s)" that can be used to uniquely
identify the choreography instance that is being performed.

David
-----Original Message-----
From: Monica Martin [mailto:monica.martin@sun.com]
Sent: Thursday, August 07, 2003 3:03 PM
To: Burdett, David
Cc: 'Martin Chapman'; 'Yves Lafon'; jdart@tibco.com; 'Ugo Corda';
'Cummins Fred A'; public-ws-chor@w3.org
Subject: Re: Correlation Requirements


Burdett, David wrote:

> A very good point Martin - I was presuming "a" solution which is 
> perhaps premature.
>
> So let's do this the "right" way and think about it in terms of 
> requirements so here's my $0.02c on what they might be ...
>
> Requirement 1
> If a message is being sent between roles as part of the "performance" 
> of a choreography, then that message MUST identify the "choreography 
> instance" to which it belongs
>
> Requirement 2
> A choreography instance MAY be identified by specifying a unique 
> identifier in "metadata" (e.g. a SOAP header) associated with the message.
>
> Requirement 3
> A choreography instance MAY be identified by referencing a combination 
> of one or items of data in the "payload(s)" (e.g. the SOAP body and/or 
> attachments) of the message.
>
mm1: I would suggest on Reqt 2 and 3 that we specify the requirement not 
the solution, of which these requirements appear to do both.  
Particularly, a choreography instance may be referenced, - do we specify 
how?

> To make these complete, we should also define, roles, performance, 
> choreography instance, metadata and payload, but that can come later!
>
> Thoughts?
>
> David
>