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RE: [ACL] Principal Identity

From: Stefan Eissing <stefan.eissing@greenbytes.de>
Date: Thu, 22 Nov 2001 10:24:12 +0100
To: "Lisa Dusseault" <lisa@xythos.com>, "Webdav WG" <w3c-dist-auth@w3c.org>
Message-ID: <NDBBKJABLJNMLJELONBKAEOBDBAA.stefan.eissing@greenbytes.de>
> From: w3c-dist-auth-request@w3.org
> [mailto:w3c-dist-auth-request@w3.org]On Behalf Of Lisa Dusseault
> Sent: Wednesday, November 21, 2001 7:35 AM
> To: Clemm, Geoff; Webdav WG
> Subject: RE: [ACL] Principal Identity
>
>
> The definition of dead properties is not clear enough to make
> that proposal
> a basis for interoperability.
>
> Since I love examples, follow me through this one:
>  - A WebDAV client software package defines a couple dead properties,
> "image-height" and "image-width" as integers.  It sets these properties on
> all images it saves & uses them later.  Obviously so far it's a dead
> property.
>  - Other clients start to use these.  Still dead, right?
>  - Custom software is added onto another WebDAV server platform
> to set these
> properties auto-magically whenever an image is uploaded.  The base server
> software is uninvolved in this process.
>  - A full WebDAV server decides to make sure that whenever these
> properties
> are set, at least they're integers.  Maybe it also checks they're not
> negative.  Other servers, however, still ignore these properties.
>  - Another DAV server decides that it can calculate this property
> on the fly
> and make sure it's always correct.  However, the calculation is expensive
> (Note that this scenario starts to sound like justification for NOT
> including properties in allprop).
>
> When do these properties stop being dead and start being live?

It depends if and where and how they are defined. Just having a property
"image-height" accepted or returned by a server does not mean anything.

If you define such a property, you should also define the expected
behaviour, its liveliness and, etc. Some servers will then implement
it, while for other servers these properties are really dead.

So, the existence of such properties on a server will not tell
a client anything about their semantics. You need to introduce
some other way to announce this to a client.

The defined way to do so, is to include these properties in the
{DAV:}supported-live-property-set. Then the client knows that the
server gives special meaning to these properties.

Coming back to <allprop/>: a dead "image-height" property would
be reported, while a live property would not be reported. A client
interested in seeing "image-height" in either case, should attach
a <include>...</include> to allprop in our proposal.

//Stefan
Received on Thursday, 22 November 2001 04:22:56 GMT

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