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Re: Exchange type issue

From: Gary Brown <gary@pi4tech.com>
Date: Sat, 04 Nov 2006 11:09:53 +0000
Message-ID: <454C7501.6050900@pi4tech.com>
To: "Monica J. Martin" <Monica.Martin@Sun.COM>
CC: Steve Ross-Talbot <steve@pi4tech.com>, Charlton Barreto <charlton_b@mac.com>, Martin Chapman <martin.chapman@oracle.com>, 'WS-Choreography List' <public-ws-chor@w3.org>

Hi Monica

There is very little difference between a notification and a response. 
The only difference really is one is coupled to a request and the other 
is not. This is how I explained the difference in my proposed changes, 
and why I think a new action type is the best approach to deal with this 
- but in the description make the distinction between 'respond' and 
'notify' clear.

If you have an alternative means of representing this distinction then I 
would be interested in discussing it.

Regards
Gary


Monica J. Martin wrote:
>
>> Steve Ross-Talbot wrote: I think the BPEL thing is a red herring. We 
>> have always been able to  model or describe more than BPEL can 
>> handle. Our concept of channel  identity is not supported by BPEL 
>> (from memory) and is much richer  than BPEL.
>>
>> The ability to have a response with not matching request is in-built  
>> into WS-CDL and always has been. What we match is not request/ 
>> response but send/receive - and interaction. A request and a 
>> response  can be modeled as two explicit interactions but can, as a  
>> convenience, be modeled in a single interaction. If we have them  
>> explicit then implementors can choose how to match (usually on  
>> operation name) but I do not think this is mandatory. When we have a  
>> request and a response in a single interaction the operation names  
>> are by definition matched - they share the same operation name.
>>
>> A notification exchange type makes explicit a pattern which in turn  
>> provides clarity of description. It becomes clear as to the intent.  
>> And this can only be a good thing. Just because BPEL doesn't support  
>> it doesn't mean we should not. Just because many Web Service stacks  
>> do not support it does not mean we should not. One day they may well  
>> support it and so by supporting what is in the standards and what 
>> the  wider non-web service community use ensures we achieve one of 
>> our  goals, namely that we all want WS-CDL to have wider utility 
>> than  current tools provide today and wider utility outside of a 
>> strictly  web service environment - hence the optional role interface 
>> in WS-CDL.
>
> mm1: I just made an observation to consider in the total scope of our 
> discussion, not to create a religious war (for others than myself). As 
> far as the exchange type, we need to discuss in detail whether the 
> issue is the need for a new exchange type or reconsideration of the 
> semantics and constraints of the current 'respond.' I'm anxiously 
> awaiting this final observation to be addressed. Thanks.
>
>
>
>
Received on Saturday, 4 November 2006 11:10:27 GMT

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