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RE: Burdett ML gap/fit analysis - first cut

From: Burdett, David <david.burdett@commerceone.com>
Date: Wed, 30 Jul 2003 17:33:58 -0700
Message-ID: <C1E0143CD365A445A4417083BF6F42CC053D1CA3@C1plenaexm07.commerceone.com>
To: "'Ugo Corda'" <UCorda@SeeBeyond.com>, "Burdett, David" <david.burdett@commerceone.com>, jdart@tibco.com
Cc: public-ws-chor@w3.org
I agree as long as we actually realize a clear distinction between the
levels and don't blur them. If you write separate specs then you are forced
to do this. If you don't then there are many temptations to take short cuts
.......
 
David

-----Original Message-----
From: Ugo Corda [mailto:UCorda@SeeBeyond.com]
Sent: Wednesday, July 30, 2003 5:30 PM
To: Burdett, David; jdart@tibco.com
Cc: public-ws-chor@w3.org
Subject: RE: Burdett ML gap/fit analysis - first cut


David,
 
I would go with a single spec that addresses the three levels of message
description, discusses the role played by each level in the choreography,
and maps these concepts to the two levels WSDL provides. Since levels 2 and
3 are already pretty well understood in the Web services community, I
imagine this exercise should primarily focus on explaining the value of
level 1 and describing its mapping to the other levels.
 
Ugo

-----Original Message-----
From: Burdett, David [mailto:david.burdett@commerceone.com]
Sent: Wednesday, July 30, 2003 5:20 PM
To: Ugo Corda; Burdett, David; jdart@tibco.com
Cc: public-ws-chor@w3.org
Subject: RE: Burdett ML gap/fit analysis - first cut



Ugo 

I agree that this needs clarification. I actually think that we could do
different specs, e.g: 
1. Three specs where there is one spec for each of the three levels 
2. Two specs where either Levels 1 and 2 are combined with a separate Level
3, or Levels 2 and 3 are combined with a separet level 1

3. A single spec covering all levels. 

I'm not sure I know what the right answer is although my best guess would be
either separate specs (i.e. option 1) or a single spec in three sections.

What are your thoughts? 

David 
-----Original Message----- 
From: Ugo Corda [ mailto:UCorda@SeeBeyond.com <mailto:UCorda@SeeBeyond.com>
] 
Sent: Wednesday, July 30, 2003 1:10 PM 
To: Burdett, David; jdart@tibco.com 
Cc: public-ws-chor@w3.org 
Subject: RE: Burdett ML gap/fit analysis - first cut 


David, 

I think I understand your levels. At the same time, your classification
makes me think that we need to better clarify how our choreography is
grounded on WSDL. In particular, we should clearly specify if and when the
specific message descriptors defined in WSDL interfaces can be used
(including things like abstract XPath selectors) when talking about messages
exchanged within our choreographies.

Without this clarification, many people would naturally infer from the WDSL
grounding that our choreography deals with messages at level 2.

Ugo 

> -----Original Message----- 
> From: Burdett, David [ mailto:david.burdett@commerceone.com
<mailto:david.burdett@commerceone.com> ] 
> Sent: Wednesday, July 30, 2003 12:45 PM 
> To: Ugo Corda; jdart@tibco.com 
> Cc: public-ws-chor@w3.org 
> Subject: RE: Burdett ML gap/fit analysis - first cut 
> 
> 
> Ugo 
> 
> I was really thinking more of the abstract binding where a 
> choreography is 
> bound to abstract messages. Except I am *not sure* that port/interface 
> levels are sufficiently abstract as you could have the same 
> sequence of 
> messages exchanged for the same purpose only they go between 
> services with 
> different port types/interfaces. 
> 
> I think there are three levels: 
> 1. The pure choreography - i.e. independent of the message 
> formats and also 
> the port types/interfaces 
> 2. Choreography bound to an abstract interface/port type 
> 3. Interface/port type bound to a specific implementation 
> 
> Do these levels make sense? 
> 
> David 
> 
> -----Original Message----- 
> From: Ugo Corda [ mailto:UCorda@SeeBeyond.com
<mailto:UCorda@SeeBeyond.com> ] 
> Sent: Wednesday, July 30, 2003 12:15 PM 
> To: Burdett, David; jdart@tibco.com 
> Cc: public-ws-chor@w3.org 
> Subject: RE: Burdett ML gap/fit analysis - first cut 
> 
> 
> 
> Dave, 
> You said: 
> 
> > Also a choreography should be able to work with multiple 
> different message 
> > formats therefore including a reference to single message 
> format directly 
> > into the choreography could be problematical. 
> 
> This depends on at which level you are talking about 
> messages. If you are 
> talking at the level of abstract messages (i.e. 
> portType/Interface level in 
> WSDL), then our choreography is based on those message 
> descriptions (this 
> comes directly from our own definition of Web services 
> choreography, i.e. 
> the fact that it is grounded on WSDL) and it should be 
> legitimate to talk 
> about those abstract message formats within the choreography itself. 
> 
> If you are talking about concrete message formats (after the 
> WSDL interfaces 
> defined in the choreography are bound to specific end points) 
> then I agree 
> with you that the choreography should not depend on them. 
> 
> Ugo 
>  
> 
Received on Wednesday, 30 July 2003 20:34:00 GMT

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