W3C home > Mailing lists > Public > www-ws-arch@w3.org > December 2002

Re: WSD Requirements: add a requirement about safe and idempotent characteristics

From: Mark Baker <distobj@acm.org>
Date: Tue, 3 Dec 2002 23:04:07 -0500
To: Assaf Arkin <arkin@intalio.com>
Cc: www-ws-arch@w3.org
Message-ID: <20021203230407.A13658@www.markbaker.ca>

Hey,

On Tue, Dec 03, 2002 at 06:26:15PM -0800, Assaf Arkin wrote:
> I definitely agree with this view, though I would not try to enforce other
> people to respect it. I would just comment that if an operation is
> implemented using GET in one situation then it should be implemented as GET
> in all situation and never as POST (and vice versa).

Interesting.  That suggests a different model than I had in mind, or
that I've seen presented by anybody before.  Is what you mean by that,
that an operation such as "getStockQuote" should use the GET method all
the time?

FWIW, in my model, there is no "getStockQuote" operation, just the "GET"
operation.  You discover it's a stock quote either after you invoke GET,
or because you discovered the URI in a context which suggests it's a
stock quote (like "<stockquote>http://foo.org/sunw...</stockquote>").

So "GET" becomes the only operation that is required for all "getFoo()"
methods.

> Regardless, the point is that we do want to allow multiple protocol bindings
> for the same operation. Even if that operation is always an HTTP POST, it
> may also be bound to SMTP. And I may have two different ways to bind it to
> HTTP POST, e.g. to use different set of headers, and two ways to bind it to
> GET, e.g to use two different set of parameters.
>
> What I want to know, regardless of how many bindings exist, and before I
> even discover all of them, is how the operation would work. I want to know
> that form the abstract point of view (input, output, etc) it would work the
> same way.

I'll hold back on providing my view of this pending the issue above.
It's a complicated issue, but I think I have a pretty good idea for how
to manage it.

> I guess we differ since I am looking at the definition of the operation in
> isolation from any specific service that offers it, and apply that view to
> any number of services that may offer it. I do the discovery at design time
> rather than run-time.

I think of it exactly the same way!

MB
-- 
Mark Baker.  Ottawa, Ontario, CANADA.   http://www.markbaker.ca

   Will distribute objects for food
Received on Tuesday, 3 December 2002 22:59:48 GMT

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