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Re: Re (2): Move and Delete (was: bind draft issues)

From: Jason Crawford <nn683849@smallcue.com>
Date: Sun, 9 Mar 2003 12:47:56 -0500
To: Edgar@EdgarSchwarz.de
Cc: w3c-dist-auth@w3.org
Message-ID: <OFA81417CA.CC023A19-ON85256CE4.005FA280@us.ibm.com>




On Saturday, 03/08/2003 at 07:25 CET,
nnEdgar___at___EdgarSchwarz.de@smallcue.com wrote:
> Hi,
> I don't have time to follow the discussion in detail at the moment
> but this post provokes a comment.
> "Clemm, Geoff" <gclemm@rational.com> wrote:
> >    From: Brian Korver [mailto:briank@xythos.com]
> >
> >    Other than loops, what are the problems unique to multiple
> >    bindings and partial MOVE?
> >
> > One example was posted in the message below:
> >
> >    From:      Clemm, Geoff [gclemm@Rational.Com]
> >    Sent:      Monday, March 03, 2003 6:34 PM
> >    Subject:   RE: Move and Delete (was: bind draft issues)
> >
> >    ...
> >    because it can cause a DELETE in one collection to cause a change
> >    in another collection, and this kind of "deletion side effect"
> >    was something we explicitly were trying to avoid.  For example,
> >    suppose /henry/has-friend/jeff and /jim/has-friend/jeff
> >    were bindings to the same collection, JEFF, and JEFF has a binding
> >    named "wife" to a resource, MARI.  Now suppose henry gets mad
> >    at jeff, and issues a "DELETE /henry/has-friend/jeff" request.
> >    But suppose at that moment someone else has a Depth:0 lock
> >    on the /henry/has-friend collection.  The result of a "best effort"
> >    deletion is the removal of the "wife" binding from JEFF.  That
> >    may be OK if you were just updating the information accessible
> >    from /henry (he isn't JEFF's friend anymore, and he's happy to
> >    purge as much information about JEFF as he can), but with multiple
> >    bindings, "best effort" deletion has now trashed the JEFF object
> >    in all the other contexts in which it is still visible (and the
> >    folks that still are his friends are still interested in that
> >    information).
What Geoff describes is very very very bad.  But I hope that even the
folks that can't implement atomic DELETE are not considering making
their incremental delete this broken.   Even if you can't implement
atomic delete, you still can't delete bindings that would still be
accessable after you did it atomically if you could.    If this prohibition
is
not clear from the spec, then the spec needs to be fixed.

> >    So we're not saying that "best effort deletion" is always a bad
thing,
> >    but we are saying that "best effort deletion" is a bad thing when
> >    you care about multiple bindings to the same resource.

> Goeff, I don't think your scenario is valid for our discussion.

I tend to agree, but it sounds like it might be for a different reason
than what I think you're saying below. (omitted)  My reason is mentioned
above.
It basically is that I think (hope) that no server is considering doing
what Geoff mentions and the non-atomic folks are only considering
something more benign if they can't do the DELETE atomicly.  I'm
hoping that the discussion is only "that more benign behavior" vs
"true atomic DELETE".




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Received on Sunday, 9 March 2003 12:52:32 GMT

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