RE: Question about "opaque" collections

From: Clemm, Geoff (gclemm@rational.com)
Date: Thu, Sep 28 2000

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    Message-ID: <3906C56A7BD1F54593344C05BD1374B10D9EB7@SUS-MA1IT01>
    From: "Clemm, Geoff" <gclemm@rational.com>
    To: ietf-dav-versioning@w3.org
    Date: Thu, 28 Sep 2000 12:03:00 -0400
    Subject: RE: Question about "opaque" collections
    
    Yes, an "opaque" collection can be versioned as a whole,
    by putting it under "baseline control" (as opposed to "version control").
    So while "version control" of a collection tracks versions of just
    that collection (i.e. it's internal members), "baseline control" of
    a collection tracks versions of all members of the collection.
    
    You can then use "SET-TARGET" and "MERGE" to bring back or merge previous
    baselines of the collection into the current state of the collection.
    
    Cheers,
    Geoff
    
    -----Original Message-----
    From: Bill Bumgarner [mailto:bbum@codefab.com]
    Sent: Thursday, September 28, 2000 11:33 AM
    To: ietf-dav-versioning@w3.org
    Subject: Question about "opaque" collections
    
    
    [I have been meaning to ask this for a while and hope that this is a repeat
    of an issue already dealt with] 
    
    
    In this less than ideal computing environments that we work with, there is
    the occasional need to revision control or configuration manage a collection
    of resources that cannot be inventoried. That is, there are applications
    that effectively use a directory [collection] as a single atomic document.
    The contents of said directory/document/collection changes with each save in
    a non-predictable fashion. As applications evolve, the documents they manage
    are becoming more and more complex. As a natural result, collection of
    resources acting as a single atomic document are becoming more and more
    common. It is interesting to note that Apple's OSX supports collections as
    documents as a first class and standard part of the desktop application
    development APIs. 
    
    
    Revision control systems such as CVS-- ones that expect the inventory of a
    directory to remain predictable across revisions-- have great dififculty
    managing such resources. For cvs, a nasty hack was implemented a number of
    years ago that effectively tarballs the collection and stores it as a
    binary, non-mergeable, resource within the repository. 
    
    
    Because the collection is effectively closed in that the contents are
    meaingless outside of the context of the collection, "opaque collection"
    seems to be a reasonable way of naming such a thing. 
    
    
    Question: 
    
    
            Can the versioning features of DAV transparently and effeciently
    store and control "opaque" collections? 
    
    
            I.e. can a collection of resources be treated as if it were a
    single, versionable resource? 
    
    
    b.bum