- From: Clemm, Geoff <gclemm@rational.com>
- Date: Wed, 27 Nov 2002 22:41:35 -0500
- To: Webdav WG <w3c-dist-auth@w3c.org>
- Message-ID: <E4F2D33B98DF7E4880884B9F0E6FDEE20129B366@SUS-MA1IT01>
Just one comment on the statement "we've already discovered since 2518 was published that locks aren't the only tool required to prevent lost updates". I disagree ... locks are sufficient to prevent lost updates. If a client decides not to use the locking protocol correctly (i.e. by updating a resource for which it does not have a valid lock), then of course something additional is required, but for a client that uses the locking protocol properly, locks are the only tool required to prevent lost updates. With that said, I personally have no objection to requiring etag support for PUT'able resources, but I am interested in hearing from any server writers for whom requiring etag support would be problematic. Cheers, Geoff -----Original Message----- From: Lisa Dusseault [mailto:lisa@xythos.com] Sent: Wednesday, November 27, 2002 9:55 PM To: Webdav WG Subject: RFC2518 issue: requiring ETags (Atlanta wg mtg) The issue of requiring ETags was brought up at the WG mtg, as one of the remaining 2518 bis issues. The discussion covered dynamic resources, and a couple possible methods to generate ETags without too much pain (using combinations of sequence numbers, timestamps, hashes of resource names or content.). Most interestingly, there was also a suggestion that ETags could be required only for resources that can be PUT to. I think I'm satisfied with this compromise, because it's precisely in the situation when a client is trying to PUT a resource body, that ETag support is needed. We've already discovered since 2518 was published that locks aren't the only tool necessary to prevent lost updates - you also need ETags. For read-only resources Etags are nice-to-have in some situations (like synchronization and caching) but there isn't the data loss possibility. Note that this would require that for any resource that supports PUT, the server MUST return the ETag header on each GET request - because the server can't tell when the GET request is received, whether the user intends to try to do a PUT later or not. Comments? Lisa
Received on Wednesday, 27 November 2002 22:42:12 UTC