Re: Write Locks on Collections

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   Date: Tue, 23 Nov 1999 23:26:13 +0100
   From: Jim Davis <jrd3@alum.mit.edu>
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   At 04:19 PM 11/23/99 -0500, Geoffrey M. Clemm wrote:
   >   A write lock on a collection, whether created by a "Depth: 0" or "Depth:
   >   infinity" lock request, prevents the addition or removal of member URIs of
   >   the collection by non-lock owners.

   >   If a lock owner causes the URI of a resource to be added as an internal
   >   member URI of a locked collection then the new resource MUST be
   >   automatically added to the lock.
   >
   >I believe this statement should only apply to non-Depth:0 locks.
   >Otherwise, this results in the inability to independently lock
   >a collection and members of the collection.  

   How so?  please provide a sequence of operations that would be impossible
   under this interpretation.

I lock a collection, because I'm going to be adding members
to that collection.  If a depth:0 lock applies to all the
immediate members of a collection as well, then I have prevented
anyone from updating the state of one of the existing internal members of
that collection.  If I'd wanted that behavior, I would have issued a
depth:1 lock.  And quoting from the definition of what depth means:

   The Depth header is used with methods executed on resources which
   could potentially have internal members to indicate whether the
   method is to be applied only to the resource ("Depth: 0"), to the
   resource and its immediate children, ("Depth: 1"), or the resource
   and all its progeny ("Depth: infinity").

Cheers,
Geoff

Received on Wednesday, 24 November 1999 11:46:09 UTC