RE: Move and Delete (was: bind draft issues)

I believe it is simpler for a client if the DELETE model stays
consistent (i.e. doesn't change when another binding is added
to a member of the collection).

Also note that it is actually quite complex to state under what
conditions it is OK to partially delete nested bindings; namely,
"when a collection is deleted, a nested binding can be deleted
from the collection only if there is exactly one binding to any
resource on the path from the collection to that nested binding".

Cheers,
Geoff

-----Original Message-----
From: Stefan Eissing [mailto:stefan.eissing@greenbytes.de]
Sent: Tuesday, March 04, 2003 3:46 AM
To: Clemm, Geoff
Cc: WebDAV
Subject: Re: Move and Delete (was: bind draft issues)


Geoff,

if I understand you correctly, you're saying that DELETE on a server
with BINDings must always first *unbind* the target (in an atomic
operation, similar to unlink in UNIX)?

I certainly agree that this is the desired behaviour if the delete 
target
has more than one binding.

Question: is it possible to accept a partial sucess DELETE, iff the
resource to be deleted has no other bindings?

//Stefan

Am Dienstag, 04.03.03, um 00:34 Uhr (Europe/Berlin) schrieb Clemm, 
Geoff:

>
> "Best effort" deletion is forbidden by the bind protocol,
> 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).
>
> 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.
>
> Cheers,
> Geoff
>
> -----Original Message-----
> From: Julian Reschke [mailto:julian.reschke@gmx.de]
> Sent: Monday, March 03, 2003 5:08 PM
> To: Clemm, Geoff; WebDAV
> Subject: RE: Move and Delete (was: bind draft issues)
>
>
>> From: w3c-dist-auth-request@w3.org
>> [mailto:w3c-dist-auth-request@w3.org]On Behalf Of Clemm, Geoff
>> Sent: Monday, March 03, 2003 10:44 PM
>> To: WebDAV
>> Subject: RE: Move and Delete (was: bind draft issues)
>>
>>
>>
>> To emphasize an earlier comment, it is true that the bind protocol
>> places constraints on how a server is allowed to implement the DELETE
>> and MOVE methods.  In particular, a server that supports the bind
>> protocol is not allowed to do a partial MOVE or a partial DELETE (even
>> though 2518 allows it).
>> ...
>
> Good catch. I remember that we discussed that at some point of time, 
> but it
> seems it was never added to the issues list.
>
> Our server indeed is able to support the BIND method and live 
> properties
> with all their semantics, yet won't do an atomic DELETE on 
> collections. I
> agree that *technically* a server that properly handles bindings 
> *could* do
> atomic deletes, but in reality, there may be reasons why you don't 
> *want*
> to.
>
> Therefore, I'd like the spec not to require a specific behaviou, or, 
> as a
> minimum, change the MUST to a SHOULD.
>
> Julian
>
> --
> <green/>bytes GmbH -- http://www.greenbytes.de -- tel:+492512807760
>

Received on Tuesday, 4 March 2003 10:11:40 UTC