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RE: Deleting versions

From: Clemm, Geoff <gclemm@rational.com>
Date: Tue, 5 Jun 2001 18:48:03 -0400
Message-ID: <3906C56A7BD1F54593344C05BD1374B1018E2434@SUS-MA1IT01>
To: DeltaV <ietf-dav-versioning@w3.org>
   From: Lisa Dusseault [mailto:lisa@xythos.com]

   If somebody who's not supposed to, gets in and changes something in
   between a MKWORKSPACE command and a ACL request, that's a serious
   problem.  Null resources help avoid that.

   It's not that somebody got their MKWORKSPACE request in ahead of
   mine --that's not the purpose of null resources at all.

My point was not that a lock can prevent somebody from
creating the workspace ahead of you, but rather that
someone locking "your" workspace is no different from
someone creating a workspace by that name before you
can lock that URL.

In particular, we are discussing two alternative sequences:
 LOCK/MKWORKSPACE/ACL/UNLOCK
or
 MKWORKSPACE/LOCK/ACL/UNLOCK

In the first sequence, the LOCK may fail (because there already
is a lock on that URL), so you tell the user "that workspace is
already in use by another user".

In the second sequence, either the MKWORKSPACE may fail (because
somebody got in and created a workspace before you) or the LOCK
may fail (because somebody got in and locked the workspace before
you).  In either case, you still tell the user "that workspace is 
already in use by another user".

So from the user's perspective, it doesn't matter whether
or not their client did a LOCK/MKWORKSPACE or a
MKWORKSPACE/LOCK.  Their request can fail because another
client "got there before them".

Cheers,
Geoff
Received on Tuesday, 5 June 2001 18:47:48 GMT

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