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RE: Variant Support for WebDAV

From: Julian Reschke <julian.reschke@gmx.de>
Date: Tue, 15 Oct 2002 10:51:46 +0200
To: "Jason Crawford" <nn683849@smallcue.com>, "'Webdav WG'" <w3c-dist-auth@w3c.org>
Message-ID: <JIEGINCHMLABHJBIGKBCAEFEFJAA.julian.reschke@gmx.de>

> From: w3c-dist-auth-request@w3.org
> [mailto:w3c-dist-auth-request@w3.org]On Behalf Of Jason Crawford
> Sent: Monday, October 14, 2002 7:28 AM
> To: Julian Reschke
> Cc: Clemm, Geoff; 'Webdav WG'
> Subject: RE: Variant Support for WebDAV
> I don't have a lot of time to spend on this given how many discussion
> threads we have
> alive right now, but just a quick comment...
> Could we possibly implement this in a way that meshes with how we handle
> live resources?   Perhaps with the dav:source property?   It can just tell
you at what
> URL's to find the variants and optionally give clues about how the
variants are
> selected?   This might actually be a good defining use-case for the
> property.
> ...

I think variants and sources are clearly different things. In HTTP,
"Variant" is a synonym for "representation" -- a resource can have many
representations, and HTTP already defines  how a server can signal depending
on which request criteria a particular variant was chosen ("variant"
header), and optionally what the more specific URI for this representation
is ("content-location" header).

Alternatively, a source of a resource is *not* a variant of the resource,
and thus should not be treated as such.

So at a minimum, a spec about variant handling in WebDAV must

- be compatible with the terminology in RFC2616
- should elevate the vary header and the content location headers to live
WebDAV properties
- should clarify the semantics variant-selection-relevant request headers
for the various WebDAV methods

On the other hand, it may also provide a framework for authoring varying
resources (and I think this is the primary target of Geoff's draft).

Last but not least: we should keep in mind that right now proper variant
handling is only possible if ugly workarounds are use if the client uses IE
as a browser (see bug report at [1] -- note that the bug is *still* present
in IE6).


[1] <http://bugs.apache.org/index.cgi/full/4118>

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Received on Tuesday, 15 October 2002 04:52:25 UTC

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