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Re: 2004-02-12 Action Item: Clarification to the OperationName feature

From: Amelia A Lewis <alewis@tibco.com>
Date: Mon, 23 Feb 2004 11:51:31 -0500
To: Glen Daniels <gdaniels@sonicsoftware.com>
Cc: distobj@acm.org, www-ws-desc@w3.org
Message-id: <20040223115131.1cf85dde.alewis@tibco.com>

[why is this being cc'd to the distributed objects mailing list at acm? 
do they want to see it?]

On Mon, 23 Feb 2004 11:32:08 -0500
Glen Daniels <gdaniels@sonicsoftware.com> wrote:
> > > OK, let's start this way.  Why do we bother with 
> > <operation> at all in 
> > > WSDL?
> > 
> > It establishes sequence and content of messages that are related.
> OK, sounds good.  So why do we care about that?

Historical reasons.  There's no particular justification for it, if
you've got a higher-level choreography/flow language that associates
messages in a more sophisticated fashion.  All you'd really need then is
to model each message inside an "input-only" or "output-only" operation,
and leave correlation to the higher-level language.

WSDL 1.1 didn't have such a beast available, so it defined simple
operations, some of which represent Very Well Known idioms
(client/server request/response on a single connection, in particular). 
Now, given that I've been the champion of several MEPs that are less
universally ubiquitous than that one, and an editor of part two, you
might expect me to defend the things ferociously, but ... they're just
icing.  Useful for simple definitions, and most definitions are simple.

There is, as Jim sapiently noted, *no* *expectation* that a particular
method, procedure, function, process, algorithm, or fast tango will be
performed when a particular message arrives.  Note that the whole notion
of strongly mapping to methods/functions/whatever (but not latin dances)
is strongly tied to the use of the request/response style, which more or
less (a great deal less, imo&e) parallels the processing that happens in
a stack-based computer language.  For other networking styles
(particularly output-first operations), it is much less easy to make a
mapping at all.

Message comes in, message goes out, what happens in between deponent
sayeth not.  Message goes out, message comes in, what happens in between
deponent sayeth not.  Message goes out.  Period.  Nothing to say, is
there?  Message comes in.  Period.  There may be something to say, or
there may not, but the WSDL spec *ain't sayin' it*.

"message exchange pattern" is a much better term than "operation", but
we *don't* want to end up in another argument about naming, please the
gods of small forest pools and sandy ocean beaches.

Amelia A. Lewis
Architect, TIBCO/Extensibility, Inc.
Received on Monday, 23 February 2004 12:00:33 UTC

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