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Re: Which operation?

From: Mark Baker <distobj@acm.org>
Date: Tue, 15 Jun 2004 10:09:05 -0400
To: paul.downey@bt.com
Cc: www-ws-desc@w3.org
Message-ID: <20040615140905.GB20032@markbaker.ca>

Good stuff, Paul ...

On Tue, Jun 15, 2004 at 11:46:20AM +0100, paul.downey@bt.com wrote:
> AIUI in the above example either:
>   1) some mechanism beyond the GED* is being used to dispatch
>      an incoming schema1 to the individual operations
>   2) there is no mechanism - this WSDL is ambiguous.

Yes, exactly.

> In the case of (1) it should be possible to describe the mechanism 
> being used in a WSDL document, e.g.:
>    - a binding specific mechanism is being used, in which case a 
>      binding specific description should be in place.
>    - it could be a generic addressing header mechanism, in which case 
>      we have extensions or F&Ps
>    - or it could be a mechanism describable in the interface, e.g.
>      another element or attribute uniquely identifies the operation.
>      Maybe this is the case a generic mechanism akin to XOP's use
>      of XQDM[1].

Yes, I outlined a number of similar options earlier this year, though I
can't find the message right now.  It was related to Umit's
OperationName feature proposal;


>    - finally it could be something completely out of band - my username
>      denotes i'm a Gold Paying Customer, or first 100 messages each day
>      are Gold, the remainder will be "bog-standard". I'm not sure what
>      we could do here in the WSDL language beyond kick it out to an
>      extension mechanism - this kind of interaction is outside of the 
>      domain of WSDL and in that scary land of "policy". 

That's possible, but I hope it could be avoided; ideally, you don't
want a message to change meaning because something outside the message
- in this case, your Gold Paying status - changes.  That introduces,
amoung other things, tighter temporal coupling between components;
consider what might happen if the message is processed 2 weeks later,
after your Gold Paying status has expired.  Self-descriptive messaging
is your friend. 8-)

> So WSDL could describe the dispatching mechanism being used via binding 
> specific mechanisms or extensions and i don't think we should do anything 
> to prevent other to attempt to recognise (2) at the cost of not being able 
> to describe all of (1) as well as other unforeseen dispatching mechanisms.

Sorry, I can't grok that.

Mark Baker.   Ottawa, Ontario, CANADA.        http://www.markbaker.ca
Received on Tuesday, 15 June 2004 10:16:03 UTC

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