- From: Francis McCabe <fgm@fla.fujitsu.com>
- Date: Wed, 27 Aug 2003 11:12:05 +0900
- To: "Burdett, David" <david.burdett@commerceone.com>
- 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
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 UTC