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Re: Correlation Requirements

From: Francis McCabe <fgm@fla.fujitsu.com>
Date: Wed, 27 Aug 2003 11:12:05 +0900
Cc: "'Monica Martin'" <monica.martin@sun.com>, "'Martin Chapman'" <martin.chapman@oracle.com>, "'Yves Lafon'" <ylafon@w3.org>, jdart@tibco.com, "'Ugo Corda'" <UCorda@SeeBeyond.com>, "'Cummins Fred A'" <fred.cummins@eds.com>, public-ws-chor@w3.org
To: "Burdett, David" <david.burdett@commerceone.com>
Message-Id: <DA9A8F22-D833-11D7-BE5F-000393A3327C@fla.fujitsu.com>

This message may be moot, but please bear with me:)

RE: Requirement 1

I think that there may well be cases where a service agent is 
participating in a choreography without it knowing! Consider legacy 
systems (and yes, even tomorrow's fully choreographed systems will 
legacy the day after) that are built today without the benefit of a 
CDL. We will want to be able to hook in such a service in with other 
services that *do* support our CDL; but a requirement that every 
message be decorated with a means of identifying the choreography 
instance will *not* be possible for a service that does not know about 
choreographies (it is just doing its thing)

Frank

On Friday, August 8, 2003, at 07:15  AM, Burdett, David wrote:

> 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
> >
>
Received on Tuesday, 26 August 2003 22:15:08 GMT

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