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Re: Simple Choreography composition suggestion

From: Steve Ross-Talbot <steve@enigmatec.net>
Date: Fri, 18 Jul 2003 09:18:58 +0100
Cc: "Ugo Corda" <UCorda@SeeBeyond.com>, "Fletcher, Tony" <Tony.Fletcher@choreology.com>, <public-ws-chor@w3.org>
To: "Martin Chapman" <martin.chapman@oracle.com>
Message-Id: <7B120B92-B8F8-11D7-BE6A-000393D13C9A@enigmatec.net>

+1 to Martin's last point about grounding.

On Thursday, July 17, 2003, at 05:27  pm, Martin Chapman wrote:

>
> 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.
>
> Martin.
>
>> -----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
>>
>>
>>
>>
>
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Received on Friday, 18 July 2003 04:19:17 GMT

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