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Re: What does WSDL describe?

From: Mark Baker <distobj@acm.org>
Date: Mon, 27 Oct 2003 09:16:17 -0500
To: Savas Parastatidis <Savas.Parastatidis@newcastle.ac.uk>
Cc: www-ws-desc@w3.org
Message-ID: <20031027091617.S9730@www.markbaker.ca>

Hi Savas,

On Mon, Oct 27, 2003 at 02:53:44AM -0000, Savas Parastatidis wrote:
> > You claim there's no operation, but there really is one, because there
> > remains a notion of "success" and "failure".  You just have to ask
> > "success and failure of what?".  The answer to that question is your
> > operation, whether or not you choose to include it in your message.
> > 
> 
> There doesn't necessarily have to be an answer. I can imagine situations
> where there isn't a requirement for a response.

I didn't say a response was required, only that the operation can fail
or succeed.  How that success or failure is signalled is another matter.

> > So it's true that you can get a whole lot done with just the "process
> > this state" implicit operation in your example - heck, EDI was built
> > around that operation (AFAICT).  But at least one more would be nice;
> > an operation for *retrieving* the state of things.
> > 
> 
> I don't use the terms "process" or "state". Sending a message is not an
> instruction to an agent to do something. It's just a message. No other
> semantics attached. Do you want to call that message "state"? That's up
> to you.

Ok, perhaps there's a nomenclature issue.  We're simply talking about
the difference between the following two things;

<orderForm1>
  <carOrMotorcycle>car</carOrMotorcycle>
  <colour>blue</colour>
  <cc>1800</cc>
  <model>blabla</model>
</orderForm1>

and

POST some-uri HTTP/1.1
Content-Type: application/order-form+xml
<orderForm1>
  <carOrMotorcycle>car</carOrMotorcycle>
  <colour>blue</colour>
  <cc>1800</cc>
  <model>blabla</model>
</orderForm1>

You and I both want those to mean the same thing, i.e. "please process
this document".

I claim the latter approach has some advantages over the former in terms
of extensibility and self-description.  But we could build large scale
systems with either approach, because integration complexity scales as
O(N), rather than O(Nlog(N)) or O(N^2) with typical SOA with service-
specific operations.

> So, I am talking about message exchange within
> this model and not the model described by REST.

That *is* the REST model.  We might use different terms and a different
approach, but we're describing the same thing.  Really.

Mark.
-- 
Mark Baker.   Ottawa, Ontario, CANADA.        http://www.markbaker.ca
Received on Monday, 27 October 2003 09:20:02 GMT

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