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re-use of version URL's [was: some comments from Chris Kaler ...]

From: Geoffrey M. Clemm <geoffrey.clemm@rational.com>
Date: Wed, 3 Jan 2001 09:03:38 -0500 (EST)
Message-Id: <200101031403.JAA26442@tantalum.atria.com>
To: ietf-dav-versioning@w3.org
CC: ckaler@microsoft.com, yarongo@crossgrain.com
OK, it looks like this is worth one more thread during last call.

As Tim pointed out, several members of the working group strongly
support MUST NOT, so let's look closely at the tradeoffs for saying
MUST NOT vs. SHOULD NOT.

I believe that recent threads on this topic have sufficiently
motivated why it is valuable for a client to be able to
count on version URL's not being re-used.  Certainly
a client certainly doesn't lose anything because of this
requirement.

So it is reasonable to conclude that those arguing for "SHOULD NOT"
are server implementors who feel that it is too costly for them
to satisfy this requirement.

In earlier threads, the response has been that a server writer can
just tack on a GUID to the version URL to guarantee it isn't re-used
(RFC-2518 describes a variety of mechanisms for cheaply creating
GUID's).  Perhaps those in favor of SHOULD NOT (Chris? Mark?) could
explain to the group why this would be a problem?

Note that several of the techniques described in 2518, don't
"guarantee" uniqueness, but rather make it extremely unlikely that
there will be a collision ... I believe that "extremely unlikely" is
sufficient for satisfying the "MUST NOT".

Cheers,
Geoff

   From: Tim_Ellison@uk.ibm.com

   This is too bad ... I strongly support "MUST" -- for all the reasons that
   you have heard already from numerous members of the working group.


   "Mark A. Hale" <mark.hale@interwoven.com> on 2001-01-02 08:59:01 PM

   I strongly support the use of SHOULD in this case.  Thanks for making the
   change.

   > I talked with Chris on the phone today, and he asked for a
   > change and a clarification
   >
   > - change the MUST to a SHOULD for the "version URL can never be re-used".
   >
   > Chris is concerned that various reasonable ways of getting version URL
   > uniqueness have a chance of collision if a given host name is mapped
   > to a new server.
   >
   > In general, I try to avoid SHOULD in favor of MUST whenever possible.
   > Since there has been a lot of debate on this issue, I suppose I can
   > live with SHOULD here.
Received on Wednesday, 3 January 2001 09:04:34 GMT

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