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RE: Yet another attempt to fix D-AC004

From: David Orchard <dorchard@bea.com>
Date: Tue, 25 Jun 2002 13:41:45 -0700
To: "'Cutler, Roger \(RogerCutler\)'" <RogerCutler@chevrontexaco.com>, "'Mark Baker'" <distobj@acm.org>, <michael.mahan@nokia.com>
Cc: <www-ws-arch@w3c.org>
Message-ID: <05fe01c21c88$b9184260$6d0ba8c0@beasys.com>

We believe that various programming models should be supported.  I'm
surprised - though given history I shouldn't be - that the notion that WSDL
is a bad thing came up as a result of discussion on loose coupling.
Certainly seems to be lots of things in web services that are bad things...
Our software manages to do what we think of as loose coupling and uses WSDL,
so we don't think they are coupled - so to speak ;-)  I hope we don't have
to (yet again) have the debate about coupling, and how it relates to
interfaces/type-checking/programming languages/version control/component
architectures/run-time availability/asynchrony/latency.

Cheers,
Dave

> -----Original Message-----
> From: www-ws-arch-request@w3.org [mailto:www-ws-arch-request@w3.org]On
> Behalf Of Cutler, Roger (RogerCutler)
> Sent: Tuesday, June 25, 2002 12:47 PM
> To: 'Mark Baker'; michael.mahan@nokia.com
> Cc: www-ws-arch@w3c.org
> Subject: RE: Yet another attempt to fix D-AC004
>
>
>
> I'm not sure why you think that early binding is such a bad
> thing.  In many
> instances late binding is a bad thing for various practical
> reasons.  I
> myself tend to avoid late binding if I possibly can.  This is
> not just me --
> it is an accepted architectural principle in our company's development
> community, and I believe that there are other companies with
> similar views.
>
> Actually, I don't think that a discussion of whether early or
> late binding
> is a "good" or "bad" thing is likely to be very productive.
> I think that
> both are necessary and both must be supported.  I would be very, very
> resistant to a suggestion that early binding should somehow
> be forbidden or
> made impossible.  If you feel that supporting late binding is
> critical I
> won't argue with you -- as long as you leave my early binding alone.
>
> -----Original Message-----
> From: Mark Baker [mailto:distobj@acm.org]
> Sent: Tuesday, June 25, 2002 2:27 PM
> To: michael.mahan@nokia.com
> Cc: www-ws-arch@w3c.org
> Subject: Re: Yet another attempt to fix D-AC004
>
>
>
> On Tue, Jun 25, 2002 at 02:57:02PM -0400,
> michael.mahan@nokia.com wrote:
> > >What does "loosely coupled" refer to here?  In my experience, the
> > >most common use is wrt coupling between interface and
> implementation,
> > >but it has other meanings.  We should be clear what we mean.
> >
> > Well, my intention was that the components are decoupled relative to
> > each other (a change in one component doesn't force a
> change in another
> > component) and also in the common use you describe above.
> If we can agree
> > on that then I can try rewording this to make it clear.
>
> Ah ok, that makes sense.  But I believe the term "late binding" (or
> similar) is typically what is used to refer to two separate software
> components and their ability to be integrated together at runtime.
>
> We haven't talked about this much as a group, but I
> personally believe that
> "late binding" is critical.  Of course, like so much else in Web
> architecture, the generic, a priori interface gives you this.
>  The IDL or
> WSDL approach provides a much earlier form of binding (not a
> good thing).
>
> > >An interface is definitely an important part of a component, but I
> > >wouldn't say that it defines the component.
> >
> > I agree - that's why I threw in the bracketed 'minimally'
> term. I was
> > also thinking that descriptors like role and
> responsibilities should
> > be included, but I was first trying to translate the
> existing text in
> > D-AC004.3.
>
> I don't really see what "minimally" adds, but I agree that describing
> components by roles and responsibilities is a good thing.
>
> > >What did you mean by "form" here?
> >
> > This was from the original text. I left it in to hopefully solicit
> > the author's intent and not throw out an expressed concept
> > indiscriminately.
>
> Sorry, I wasn't looking at the original when I responded.
>
> > The original text defines component relationships as
> > 1. messages
> > 2. protocols by means of which these messages are transmitted
> >
> > I was trying to express this. Do you disagree with the level of
> > abstraction
> > here (component relationship) or the verbiage?
>
> The verbiage, I guess.  I disagree that a protocol, even an
> application
> protocol, defines or describes much of the relationship
> between components,
> except where that relationship relates to the interface (which an
> application protocol does define).
>
> As an example, HTTP clients and proxies both speak HTTP, but the
> relationship between them is mostly independant of that(*);
> it's that a
> client can use a proxy to add some value to its connection with origin
> servers and gateways (such as getting it over a firewall, or
> performing
> language conversion, etc..).
>
> (*) HTTP proxy authentication would be the one part of the
> interface that
> does relate to the relationship between a client and a proxy.
>
> > >Well, we've talked about using SMTP and HTTP for Web services, for
> > >example, and those don't use XML.  So I'd like to remove
> this one.
> > >I'd suggest toning it down, but as it's a requirement, it
> wouldn't do
> > >much good to do that, so might as well remove it.
> >
> > In the vein of toning it down, maybe replace 'use' with 'support'.
>
> Good idea.  That both tones it down, and makes it measurable.
>
> MB
> --
> Mark Baker, CTO, Idokorro Mobile (formerly Planetfred)
> Ottawa, Ontario, CANADA.               distobj@acm.org
> http://www.markbaker.ca        http://www.idokorro.com
>
>
>
Received on Tuesday, 25 June 2002 16:42:25 GMT

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