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Re: question: relation between WS-CDL and WSCI

From: Nickolas Kavantzas <nickolas.kavantzas@oracle.com>
Date: Fri, 16 Apr 2004 14:43:04 -0700
Message-ID: <40805368.286FBB58@oracle.com>
To: dumitru.roman@deri.ie, UCorda@SeeBeyond.com, public-ws-chor@w3.org


I would suggest to go back to the WS-Choreo list archieves (~1y back) and
check the global vs endpoint vs mixed model threads (there are so many there)!!!

My personal opinion is that when you want to model a real peer-to-peer collaboration,
such as order management with change/cancel messages,
you need to have a global model since you have to account properly for
the race-conditions in the complete system. The view of an endpoint is not
enough to capture the intentions for how to resolve these races.

It is interesting that you mentioned the WS-FM04 workshop/conference. I was
in the program committee and gave a presentation about this issue. I have
posted my presentation in the WS-Choreo list and you can check for the details.


Ugo Corda wrote:

  > is the job of the travel agents to discover the "credit check" service

  > and adapt their choreographies to the "non-global model"
  > choreography of the "credit check" service

  It seems to me that a BPEL abstract process might be a better model for
  what you are trying to do in this case.


  > -----Original Message-----
  > From: public-ws-chor-request@w3.org
  > [mailto:public-ws-chor-request@w3.org] On Behalf Of Titi Roman
  > Sent: Friday, April 16, 2004 8:02 PM
  > To: Nickolas Kavantzas
  > Cc: WS-Choreography List
  > Subject: Re: question: relation between WS-CDL and WSCI
  > Hi Nick,
  > Thanks for your answer. See just some questions/comments
  > in-line that just crossed my mind.
  > ----- Original Message -----
  > From: Nickolas Kavantzas <nickolas.kavantzas@oracle.com>
  > To: Titi Roman <dumitru.roman@deri.ie>
  > Cc: Assaf Arkin <arkin@intalio.com>; WS-Choreography List
  > <public-ws-chor@w3.org>
  > Sent: Thursday, April 15, 2004 8:14 PM
  > Subject: Re: question: relation between WS-CDL and WSCI
  > >
  > > See comments about WS-CDL below.
  > >
  > > --
  > > Nick
  > >
  > > >
  > > > As far as I understood and please correct me if I am wrong, WS-CDL
  > supports
  > > > only "global model"(i.e. the multi-participant view of the overall
  > message
  > > > exchange) - this sounds to me as a static linking between web
  > > > services.
  > What
  > > > about the dynamic linking between ws from the point of view if
  > > > coneversation?
  > >
  > > Why does the global model implies static linking? I am not sure I
  > understand this.
  > >
  > > And what is the dynamic linking between ws from the point
  > of view of
  > > the coneversation? Can you elaborate on this more?
  > What I meant by this was that when you specify a choreography
  > all the participants are known a-priori (static linking).
  > What I miss is: I want to make a service accessible through
  > the internet and I want to describe in a language (hopefully
  > WS-CDL) how it behaves when someone uses it - note that I do
  > not need a "global model" to do this since I do not care who
  > will use it (e.g. a "credit check" service will offer its
  > service to potentially thousands of travel agents - it is not
  > the job of the "credit check" service to conform to the
  > thousands choreographies of the travel agents, but is the job
  > of the travel agents to discover the "credit check" service
  > and adapt their choreographies to the "non-global model"
  > choreography of the "credit check" service (i.e. dynamic
  > linking)) - is it possible to describe the way "credit check"
  > service behaves in my scenario in WS-CDL? if yes, I
  > personally find it very unintuitive in this, I suppose, very
  > realistic scenario(I understood from your mail that you and
  > Steve have a proposal related to this issue - is it possible
  > for me to have access to
  > it?)
  > As you can see my example is in the context of section
  > " Variation 2" of your current draft on requirements
  > - while it can be the case for the "credit check"  service
  > (new credit bureau) to "join" the travel agent choreography,
  > it can also be the case (and I personally believe that it is
  > very realistic) for the travel agent to join the "non-global
  > model" choreography of the "credit check" service(which I
  > tried to point out in the above example). Then why not just
  > add another requirement(e.g. "A sub-choreography must be
  > generated and integrated in the "global model" choreography
  > for each service discovered and used o the fly") and try to
  > tackle also this, I believe very natural problem, in the
  > choreography language?
  > Thanks a lot and I will surely read carefully the other
  > comments from you and Steve's last email and I'll come up
  > with new questions ;-). Titi Roman
  > >
  > > > What about the view of the overall message exchange as
  > seen from one
  > > > participant? Isn't WS-CDL supposed to support also this view?
  > > >
  > >
  > > I have filled an issue for this in the Cambridge F2F and myself and
  > > Steve
  > have
  > > an action item to present our proposal to the group.
  > >
Received on Friday, 16 April 2004 17:57:11 UTC

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