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RE: Simple Choreography composition suggestion

From: Martin Chapman <martin.chapman@oracle.com>
Date: Thu, 17 Jul 2003 09:27:17 -0700
To: "Ugo Corda" <UCorda@SeeBeyond.com>, "Fletcher, Tony" <Tony.Fletcher@choreology.com>, <public-ws-chor@w3.org>
Message-ID: <PEEBJKKCFNCENDPJDEMIAEFFDHAA.martin.chapman@oracle.com>

We really are talking about different views of the same thing. if your view
is the single point (e.g. a bpel process) then you are conecrned about
composing other WSDL/bpel processes - all you desribe are the other web
servuces that fan in and fan out from the single point. if your view is the
global model, then you are concerned about the message flows between all
parties in the system, not a single fan-in/fan out perspective. We need to
concern oursleves with composing the defintions of global model elements,
and that all depends on the grounding discussiion we are having.


> -----Original Message-----
> From: public-ws-chor-request@w3.org
> [mailto:public-ws-chor-request@w3.org]On Behalf Of Ugo Corda
> Sent: Wednesday, July 16, 2003 1:40 PM
> To: Fletcher, Tony; public-ws-chor@w3.org
> Subject: RE: Simple Choreography composition suggestion
> > The point I disagree with is the notion that something is not a
> > Choreography if somewhere, at some level it involves 'orchestration'
> > within a single system.
> I completely agree with you. If we take BPEL as an example of
> orchestration, then the BPEL process interacts with a bunch of
> Web services, and the process itself is a Web service (by
> definition). So we have a few Web services (the BPEL process
> itself plus the other Web services that BPEL interacts with)
> which exchange messages among themselves - messages which most
> likely involves a change of state of the various Web services
> involved. So this configuration of Web services should be
> describable via a choreography (by definition).
> For instance, let's look at the Purchase Order process described
> in BPEL 1.1 (sec. 6.1) as a concrete example. Seen from "outside"
> this BPEL process is just a Web service exposing a
> purchaseOrderPT portType, so it can take part in any choreography
> where other Web services interact with this one using that
> particular portType.
> But if we look "inside" the Purchase Order Web service itself, we
> find out that it also interacts with other "internal" Web
> services, i.e. the Invoice, Scheduling and Shipping Web services
> (by sending messages to those Web services and by receiving
> messages from them on its invoiceCallbackPT and
> shippingCallbackPT portTypes - all these message exchanges being
> controlled by the BPEL process itself). So we can in principle
> describe these four Web services and their interactions using
> another choreography. And this latter choreography composes (i.e.
> interacts) with the former one via messages exchanged over the
> purchaseOrderPT portType.
> Ugo
Received on Thursday, 17 July 2003 12:27:08 UTC

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