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RE: Valid representations, canonical representations, and what the SW needs from the Web...

From: Julian Reschke <julian.reschke@gmx.de>
Date: Sun, 2 Feb 2003 22:00:10 +0100
To: <Patrick.Stickler@nokia.com>, <julian.reschke@gmx.de>, <www-tag@w3.org>
Message-ID: <JIEGINCHMLABHJBIGKBCOEBBGGAA.julian.reschke@gmx.de>

> From: www-tag-request@w3.org [mailto:www-tag-request@w3.org]On Behalf Of
> Patrick.Stickler@nokia.com
> Sent: Sunday, February 02, 2003 5:51 PM
> To: julian.reschke@gmx.de; www-tag@w3.org
> Subject: RE: Valid representations, canonical representations, and what
> the SW needs from the Web...
>
> ...
> > I'm still not sure that I follow you that a RDDL document can't be a
> > representation of a namespace. If a textual description of a
> > namespace can't
> > be used as a representation, what else?
>
> But the content of a RDDL document is largely information not
> inherent in the XML namespace of which it is supposedly a
> "representation".

I think this largely depends on what the author puts in, right?

> > Or are you saying that there
> > actually *isn't* a valid representation for a namespace?
>
> No. I would accept an enumeration of names grounded in that namespace
> to be a valid representation of the namespace (and if folks consider
> a namespace to be infinite, which technically, I guess it is, then
> an enumeration of the names in-use or explicitly identified as
> usable/significant/whatever by the namespace owner).

I assume that XHTML would be ok? I think that's what RDDL is (or at least
used to be).

> But most/all of a RDDL document says nothing about the namespace,
> but about other resources in some way related to the namespace.
> It's like a representation of Paris describing all the cities of
> Europe because Paris is in Europe.

I'd say it's like a document saying something generic about Paris, and
containing links to additional information like shop directories, maps,
events. Exactly what I'd want it to be.

> The vocabularies, models, stylesheets, etc. identified and described
> in a RDDL document are not part of the namespace. They are merely

Yes.

> related to the namespace because the utilize names grounded in that
> namespace, and hence I consider such verbose descriptions of
> *primarily other* resources in a "representation" of an XML namespace
> to be a deviation/violation of the Web/REST architecture.

Again, that depends on what the author puts into the RDDL document, right?

> ...
>
> > > Granted, typical browser users are not used to thinking about
> > > metadata, but that doesn't mean they would not understand and
> > > welcome a means to ask a server "Tell me about this thing"
> > > rather than "Show me this thing".
> >
> > Well, they can do that right now.
> >
> > What's not really possible right now is to have metadata for
> > a resource
> > (PROPFIND succeeds) with no representation (GET/HEAD fail),
> > because that's
> > not really compatible with the underlying model (PROPFIND for
> > non-collection
> > resources basically being an extended HEAD method with XML
> > marshalling).
>
> Well, if that's true, then WebDAV definitely fails as a solution
> to standardized access to resource metadata, since one would expect
> to be able to use the same solution for all resources, whether or
> not any representation is available.
>
> Pity...

OK. So how do we expect HEAD to behave when no representation is available?

Julian

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Received on Sunday, 2 February 2003 16:00:47 GMT

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