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Re: FW: LC Comments: Web Method Feature

From: Mark Baker <distobj@acm.org>
Date: Wed, 3 Jul 2002 10:02:32 -0400
To: "Williams, Stuart" <skw@hplb.hpl.hp.com>
Cc: "'xml-dist-app@w3.org'" <xml-dist-app@w3.org>
Message-ID: <20020703100232.F10550@www.markbaker.ca>

Hey,

On Wed, Jul 03, 2002 at 09:42:44AM +0100, Williams, Stuart wrote:
> Clearly our opinions differ...
> 
> If the user of a binding (a SOAP processor) has access to a binding within
> it's local environment and that binding claims to support a given MEP that
> the binding user understand then IMO it should be able to make use of that
> MEP successfully without regard for other features supported by the binding
> that the binding user either does not understand or chooses not to use.

Mostly, yes, but modulo the restrictions on the MEP implicit in the
implementation of the underlying protocol.  For example, the
Request-Response MEP doesn't make much sense for HTTP 1.1 GET or DELETE,
because neither can transfer a SOAP envelope on a request.

> IMO, as currently written in the HTTP binding, the user of the SOAP-Response
> and Request-Response MEPs need to understand and use the Web Method feature
> in order to successfully use these MEPs. IMO this is a mistake and breaks
> the intent of the framework.  Neither MEP specification indicates a critical
> dependency on use of the Web Method feature, which is correct IMO.

Good point.  I disagree with you, but I think that we should say
something about the dependancy.

> The Web Method feature allows for binding users that understand it to make
> use of it... that's fine... It happens that support for the Web Method
> Feature is mandated for the HTTP binding in Part 2 and binding users that
> wish to use it are free to do so. Equally, binding users that do not
> understand it or choose not to use it should also be free to do so.
> 
> As for 'a priori' othogonal (although I'm not sure what you intend to
> communicate with the 'a priori' prefix)...

See below.

> Should I be able to use PUT,POST
> or DELETE in conjunction with the SOAP-Response MEP (and if so, how is a
> responding SOAP node to determine that the SOAP-Response MEP is in
> operation)?

I'd say that you should be able to use it with all those methods.

I'm not sure why the responding node would need to know which MEP was in
use though, at least when bound to an application protocol.  In that
case, the MEPs exist to describe the combination of the implicit MEP-
impacting features of the protocol, plus how its abstracted for the
developer.  For example, neither HTTP, nor an HTTP server, needs to know
that the SOAP-Response MEP is in use in order to be able to respond to a
GET with a SOAP envelope.  SOAP-Response is just an abstraction used to
permit clean separation of responsibilities at the sending node.

>Should I be able to use GET in conjunction with the
> Request-Response MEP (and if so, how is a responding SOAP node to determine
> that the Request-Response MEP is in operation)?

Not in conjunction with HTTP 1.1, since GET can't transfer a SOAP
message.  But perhaps some future HTTP-like protocol with its own GET
could do that.

> And if there are
> restrictions on Web Method usage in combination with particular MEPs how
> then are they "orthogonal"?

They're orthogonal until an underlying protocol is bound, which
introduces implementation details that may impact the ability of a MEP
to be supported.  Hence "a priori orthogonal".

MB
-- 
Mark Baker, CTO, Idokorro Mobile (formerly Planetfred)
Ottawa, Ontario, CANADA.               distobj@acm.org
http://www.markbaker.ca        http://www.idokorro.com
Received on Wednesday, 3 July 2002 09:51:38 GMT

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