Re: Most recent vs. specific version (was versioned collections: a p roposal)

Geoffrey M. Clemm (gclemm@tantalum.atria.com)
Mon, 9 Nov 1998 14:35:29 -0500


Date: Mon, 9 Nov 1998 14:35:29 -0500
Message-Id: <9811091935.AA00398@tantalum>
From: "Geoffrey M. Clemm" <gclemm@tantalum.atria.com>
To: barbarab@pcdocs.com
Cc: ietf-dav-versioning@w3.org
In-Reply-To: <6744FE232274D111BF8600A0C92065AA01404F32@EXCHANGE-BOS> (message
Subject: Re: Most recent vs. specific version (was  versioned collections: a p 	roposal)


   From: Barbara Bazemore <barbarab@pcdocs.com>

      From: Geoffrey M. Clemm [mailto:gclemm@tantalum.atria.com]
      Sent: Monday, November 09, 1998 7:14 AM
      To: ietf-dav-versioning@w3.org
      Subject: versioned collections: a proposal

      [...]

      To support versioned collections, I propose that the members of a
      revision of a versioned collection should be *references* to other
      *versioned resources* (not the versioned resource itself, nor a
      references to particular revisions). 
      [...]
      The contents of:

	http://www.rational.com/web-dav/repo/test/src.dir,v/r2.1

      would then be lines of text such as:

	hello.c <http://www.rational.com/web-dav/repo/test/hello.c,v>
	print.c <http://www.rational.com/web-dav/repo/test/print.c,v>
	inc     <http://www.rational.com/web-dav/repo/test/inc.dir,v>

      [...]

   Often collections should contain the most recent version of each of their
   members.  However, I believe that there are times when you want to refer to
   a specific version of
   a member.  This should be supported.  For example, the 3rd quarter 1998
   results might point to specific versions of the balance sheet, the
   president's message, the auditor's message, etc.  You wouldn't want the 3rd
   quarter results changing every time someone checked in a new version of the
   balance sheet.

Just to avoid any confusion, the contents of src.dir,v/r2.1 above does
not mean "select the default revision of each of these versioned resources".
Rather it just means "Here is a list of versioned resources with the
path segment that names them in this collection revision".
You would select revisions (default, fixed, whatever) in a *configuration*
XML element (see the original proposal message for details).

   Sometimes you may want to package up a collection containing different
   versions of the same document.  For example, the 1998 report might contain
   the 3rd quarter balance sheets for 1996, 1997 and 1998.

   Therefore, it would be nice to define a syntax for specifying a particular
   version as well as a standard way of specifying most recent version.

Simple configurations (such as LABEL-CONFIGURATION) would not allow
you to do this (since a label can select at most one revision of a
given versioned resource), but more advanced configurations, that let
you use different rules for different URI's would handle this just
fine.

In summary, these are all reasonable things to want to do, and I believe
the proposal provides an extensible mechanism and syntax for doing so.
If this mechanism is found acceptable, we could start an interesting
thread on the set of configuration elements that we feel should be
pre-defined.

Cheers,
Geoff