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Re: getlastmodified & properties

From: Greg Stein <gstein@lyra.org>
Date: Sun, 01 Aug 1999 00:47:45 -0700
Message-ID: <37A3FBA1.536ED9E@lyra.org>
To: Douglas Steen <dsteen@connectionpoints.com>
CC: w3c-dist-auth@w3.org
Hey Dug...

Douglas Steen wrote:
> RFC 2518, 13.7 reads (in part):
>   "Note that the last-modified date on a resource may reflect changes in
> any part of the state of the resource, not necessarily just a change to
> the response to the GET method."
> I'd like to assume that the last-modified date _will_ reflect changes to
> any part of the state (such as a property change).  I know that this is
> the case for IIS5, but I'm wondering if other servers are changing the
> last-modified date when properties are updated, even though it's not
> officially required.
> Does anyone know whether this is an unwritten standard, or just a
> coincidence for IIS5?

Coincidence for IIS5.

mod_dav uses the timestamp from the underlying file. Therefore, property
changes will not update the last-modified time.

It will be difficult for some systems to respond with timestamps for
property changes because of the underlying storage system and/or the use
of live properties. In the mod_dav case, it would be "expensive" to
check for property change times because it would need to consult a
separate data store (in addition to the filesystem). Note that live
properties can change at a whim of the server; as a result, it could
render the last-modified meaningless because it could change almost
continually (tracking the live property change).

Anyhow: my recommendation would be to not rely on property changes (in
any server) to update the last-modified timestamp.


Greg Stein, http://www.lyra.org/
Received on Sunday, 1 August 1999 03:49:24 UTC

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