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Re: One lock per resource per person?

From: <jamsden@us.ibm.com>
Date: Fri, 15 Oct 1999 15:31:53 -0400
To: w3c-dist-auth@w3.org
Message-ID: <8525680B.006B6FBF.00@d54mta03.raleigh.ibm.com>


A principal can only have one lock on a resource. If the lock is exclusive, then
there can only be one. If the lock is shared, then getting another shared lock
would not give owning principal any further capability. I don't have the spec if
front of me, but I believe this is spelled out.






ccjason@us.ibm.com on 10/15/99 03:13:59 PM

To:   w3c-dist-auth@w3.org
cc:

Subject:  One lock per resource per person?




In an offline discussion, the following question came up...

   Is it possible for a single principle to have multiple locks per resource?

I'd like to hear some opinions... but here are some mental exercises...

Lock tokens were invented to deal with the situation where the left hand and the
right hand don't know what each other is doing.   Otherwise it would be
sufficient to be authenticated as the entity that owns the lock.  It's important
to actually hold the lock to demonstrate awareness of it.  (It's also why we
supposedly also have to be careful how we use lockdiscovery.)

This philosophy suggests that there can only be a single exclusive lock on a
resource.  No exceptions.  If the left hand and right hand really know that they
won't step on each other... they can simply use the same lock token.   Even the
owner of the existing exclusive lock can't get another of the same type.  I
suppose the one possible exception would be if they submit the existing lock
token.  Buf for now I'll suggest that there can only be one exclusive lock per
resource.  Period.

This leaves the case of shared locks.   I think the answer here is different.
We don't exclude different people from holding the same lock.  Why should we
exclude the right hand and left hand?  Also in the case of...

   /a/b

I believe PersonX can already shared depth lock /a/ and still have another
shared lock on /a/b.  So I believe it's already possible for one principal to
have multiple locks per resource.

Comments?

Do we require a modification to 2518?

------------------------------------------
Phone: 914-784-7569,   ccjason@us.ibm.com
Received on Friday, 15 October 1999 15:34:09 GMT

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