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Re: RFC2518 (WebDAV) / RFC2396 (URI) inconsistency

From: Roy T. Fielding <fielding@ebuilt.com>
Date: Tue, 20 Nov 2001 10:57:54 -0800
To: Julian Reschke <julian.reschke@greenbytes.de>
Cc: Matt Timmermans <mtimmerm@opentext.com>, w3c-dist-auth@w3.org, uri@w3.org
Message-ID: <20011120105754.B1306@waka.ebuilt.net>
> > More arbitrary than defining a new URI scheme *and* using xmlns just to
> > replace DAV: with D:?  Just choose one, please.  Why on earth would we
> 
> With all due respect, I think this shows a misunderstanding of the role of
> XML namespaces in WebDAV. There are a lot of reasons for WebDAV to use XML
> namespaces - it's not just a syntactic matter whether to write
> DAV:multistatus or D:multistatus.

Well, that's the only example I've seen in use.

> First of all, without namespace declaration, an element named
> DAV:multistatus wouldn't be NS-wellformed. In addition,

Should I take that to mean only namespaces can have ":" in the tag name?
That would explain a lot.

> - WebDAV messages can be extended with "arbitrary" new extension elements,
> preferrably from other namespaces (just like other XML applications do),

Yes, but those will presumably be in another (well-formed) namespace.

> - WebDAV has a resource property model where a property is identified by the
> pair (namespace, element name).

Isn't it reasonable to have a default namespace in the property model?

> So, having XML namespaces in WebDAV has really nothing to do with the syntax
> for the prefix.

I didn't say it did.  I said that treating DAV: as both a namespace and a
URI scheme is wrong (and confusing).  The reasons for doing so at the time
were because xmlns was being developed (slowly) at the same time as WebDAV.

> Of course I do agree that choosing "DAV:" as namespace name was a bad idea.
> 
> > want to change the definition of URI in 2396 to allow
> >
> >    scheme:
> >
> > to be a valid URI?  It isn't a valid URI.
> 
> (Side remark: good old Microsoft is even using namespace names like "xml:").
> 
> Not according to the current grammar, right.

Then it sounds to me like the xmlns attribute does not contain a URI.
It contains a URI prefix.

> However, if you look at [1] you'll find that although TBL made his comments
> about the DAV: URI scheme himself, he didn't catch the greater problem if
> not being a URI at all. I think this says something about the *intent* of
> RFC2396 :-)

Yeah, it says that we never considered that someone would try to use the
grammar incorrectly within a specification.  We naturally assume that
people want the value to be a URI if they say it contans a URI.

> > As you said, RFC 2518 was based on an early draft of XML namespaces, and
> > it will need to be updated for that in any case (or stop using xmlns).
> 
> Again, this is on the list of known and resolved issues.
> 
> [1] <http://lists.w3.org/Archives/Public/w3c-dist-auth/2001JanMar/0166.html>

I don't see that as being resolved, unless the WG is going to bite the
bullet and follow Tim's recommendation.

....Roy
Received on Tuesday, 20 November 2001 14:01:11 GMT

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