Re: configurations and all that...

Geoffrey M. Clemm (gclemm@tantalum.atria.com)
Fri, 7 May 1999 12:03:50 -0400 

Date: Fri, 7 May 1999 12:03:50 -0400
Message-Id: <9905071603.AA08668@tantalum>
From: "Geoffrey M. Clemm" <gclemm@tantalum.atria.com>
To: sv@crystaliz.com
Cc: ietf-dav-versioning@w3.org
In-Reply-To: <009a01be80f6$a113eba0$e6ea7392@honeybee> (sv@crystaliz.com)
Subject: Re: configurations and all that...


I'm working my way into my "backlog" of unanswered email, so apologies
for any "time-warp" effect this might have.  In this case, after a month
all these issues continue to be valid, so if you didn't look at the date
of this message, you probably wouldn't know it was from a month ago (:-).


   From: "Sankar Virdhagriswaran" <sv@crystaliz.com>
   Date: Wed, 7 Apr 1999 08:59:32 -0400

   Jeff,

   I have not read through your note in detail. But, I must say that I find the
   distinction you made matches exactly with my model of the world. I think
   your note brings up the key issues that I have been struggling with. To me
   the user model is as follows: Groups
   of
   authors are operating in parallel on deeply nested collections. Workspaces
   are mechanism to provide a 'selection' (i.e., a view) of the collections and
   items within these collections that are revision controlled.

Sounds right to me.

   I have excerpted statements from your message that I agree to and I hope the
   design team would also take a look at them:

   1. "Let's turn the table a little and focus on the user view.  Users have
   (potentially numerous and deep) collections of resource revisions
   identified by workspace RSRs and they want to capture them (perhaps
   independently) for later reuse.  They might have all manner of stuff in
   their workspaces.  Some of it ready to go to production, some just
   starting prototyping.  The workspace is not the focus, the collections of
   resources are.  The workspace is the view onto, or context for, the
   resources (i.e., specs revisions via RSRs) but that's it."

Agree again.

   2. "Other WebDAV
   people have been working hard on collection semantics.  I suspect that
   versioning will have many of the same issues.  It would be great if we
   could derive our semantics from theirs so we appear as a simple variation
   (if at all)."

And agree again (which is one reason why JimW and I are active participants
on the advanced collections design team).

   3. "While these components
   are often shared, exchanged, shipped, ... (whatever) in groups, the
   grouping may change from operation to operation or user to user."

Not quite sure what you have in mind here ... could you expand a bit?

   4. "Prerequisites (i.e., needed configs) are useful ways
   for users to group/reuse logically coherent resource sets but BEWARE!
    Maintaining these dependencies is a NON-TRIVIAL amount of work for the
   user."

There are many (actually, *very* many) different kinds of interesting
dependencies, with a variety of semantics.  The dependencies that the
versioning team is focusing on is a very specific kind, namely a
dependendency that affects revision selection.  In particular, if a
revision selection element "depends" on another artifact, that other
artifact is implicitly added to the revision-selection-rule.  This
constrained form of dependency with specific semantics is more manageable
than the general form.

   5. "I sure hope configurations have a lightweight
   implementation (in both speed and space)."

Amen.

   6. "Users are going to define this granularity.  For some, the
   collections they want to deep revision contain whole websites and they
   will have only one collection, for others they contain one part of one
   component and they have thousands.  It is whatever makes sense for the
   user's domain.  We would do well to not make too many assumptions about
   this."

Yes.

Cheers,
Geoff