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RE: DAV Schema Assessment (was Re: rfc2518bis DAV DTD ...)

From: Julian Reschke <julian.reschke@gmx.de>
Date: Thu, 16 Oct 2003 22:18:52 +0200
To: <dennis.hamilton@acm.org>, "Stanley Guan" <stanley.guan@oracle.com>, <w3c-dist-auth@w3.org>
Message-ID: <JIEGINCHMLABHJBIGKBCAEENINAA.julian.reschke@gmx.de>

> From: w3c-dist-auth-request@w3.org
> [mailto:w3c-dist-auth-request@w3.org]On Behalf Of Dennis E. Hamilton
> Sent: Thursday, October 16, 2003 10:02 PM
> To: Julian Reschke; Stanley Guan; w3c-dist-auth@w3.org
> Subject: RE: DAV Schema Assessment (was Re: rfc2518bis DAV DTD ...)
>
>
>
> Julian,
>
> With regard to schema-definition maintenance, I was referring
> only to extension to the DAV: namespace, not the occurrence of ad
> hoc elements from other namespaces.

OK,

yes, you can define a Schema that knows about all presently defined DAV
elements. If you combine that with lax validation for non-DAV elements, and
also take care of all other issues (such as ordering), you may be able to
use that for validation. However, this validation immediately breaks once a
new DAV protocol element is added. Thus, you can't use that Schema to
validate messages in a production system that is meant to accept messages
with not-yet defined extensions.

> ...
>
> The only case that a reference XML schema definition for DAV
> would need to be maintained is with regard to the first part.
> The second case is up to the people who define/use ad hoc
> additions. [Because there is no 100%, I see no reason to settle
> for 0%.  It's not a binary question for me.]

Well, the validation process MUST accept all messages that are legal
according to the spec. If it doesn't, what's the point in using it (unless
just for debugging/education reasons)?

> Does that fit your understanding of DAV extensibility?
>
> If you're telling me that anyone can invent an element and
> DAV-validly introduce it as if under the DAV namespace, I will

The WG says it's not allowed, but many companies do it. That's a fact we
can't change in practice.

> quietly pick up my marbles and go figure out how to use SOAP
> (with attachments) and the Web Services stack on HTTP to do
> Document Authoring and Versioning on the web. (Such an expression
> of some level of DAV functionality is probably valuable anyway.)

I'm not sure I follow. The way WebDAV is extensible IMHO doesn't cause any
actual problems. Please be more specific. And before promoting SOAP in a
HTTP-based WG, please make sure that you've read all related
HTTP-with-extensions-vs-SOAP propaganda :-)

Julian

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Received on Thursday, 16 October 2003 16:19:19 GMT

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