Re: Locking revisions

From: Geoffrey M. Clemm (geoffrey.clemm@rational.com)
Date: Sat, May 06 2000

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    Date: Sat, 6 May 2000 17:41:43 -0400 (EDT)
    Message-Id: <200005062141.RAA18417@tantalum.atria.com>
    From: "Geoffrey M. Clemm" <geoffrey.clemm@rational.com>
    To: ietf-dav-versioning@w3.org
    Subject: Re: Locking revisions
    
    
       From: "Tim Ellison/OTT/OTI" <Tim_Ellison@oti.com>
    
       Taking out a lock on a URL whose target is a revision should be
       allowed, but is a trivial case.  The revision properties and
       content are protected, so other clients cannot be making
       conflicting changes.
    
    A "lock" has two effects.
    
    The first is that it ensures that the state of the resource cannot be
    modified without the lock token.  I agree that this is trivial for
    revisions, since you can't modify the state anyway, with or without a
    lock token.
    
    The second is that it ensures that the lock token is required in order
    to cause the locked URL to identify a different resource.  In the case
    of a stable URL, this is also trivial, since a client is not allowed
    to change which revision is identified by a stable URL.  But in case
    of a URL that identifies a versioned resource, the association between
    that URL and a revision can be changed with a SET-TARGET or CHECKIN
    request.  So a lock both ensures that without the lock token, you
    can't associate the URL with a different versioned resource, and you
    can't change the target.
    
       Although there are mutable properties on a
       revision, it does not make sense to prevent the server from
       modifying these (i.e., failing merge requests etc.).
    
    I agree.  Locks only apply to dead properties (the only
    dead properties defined in the versioning protocol are DAV:author
    and DAV:comment).
    
    Cheers,
    Geoff