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RE: checked-out VCC (was: Re: Versioning TeleConf Agenda, 4/6/01 (Friday) 12-1pm EST)

From: <Tim_Ellison@uk.ibm.com>
Date: Wed, 11 Apr 2001 14:38:16 +0100
To: ietf-dav-versioning@w3.org
Message-ID: <80256A2B.004AEA8B.00@d06mta07.portsmouth.uk.ibm.com>


Geoff wrote:
> In versioning, a good way of determining what the "state"
> of a version-controlled resource consists of, is to create
> a version of it, and see what is stored in that version.

'suppose that depends on your definition of 'good'.  Since we are talking
about configurations it could be a good way of using up lots of server
cycles and disk space.
In general it should be possible to just query the state of the
version-controlled resource directly without having to make a version of
it.  (I could take a photo of you to see what you look like, but if you are
there for the photo...)

> If you create a version (i.e. baseline) of a version-controlled
> configuration, you see a snapshot of the state of all
> members of the configuration rooted at the baseline-controlled
> collection.

This is true.

> I believe this is a compelling argument for the
> statement that the state of the version-controlled configuration
> is the state of the configuration rooted at the baseline-
> controlled collection (also, that's what the protocol says :-).

I agree with the conclusion, but don't see that as a compelling argument.

The version-controlled configuration represents the deep hierarchy of
version-controlled resources rooted at the baseline-controlled collection,
and is only necessary to distinguish operations on the configuration from
those on the (shallow) root collection.  Had we chosen some other mechanism
then there would be no need for the version-controlled configuration.

Just as a version-controlled resource can differ from the checked-out
version to which it refers, there is every reason to believe that the
version-controlled configuration can differ from the baseline.  This
implies (to me) that it may be in the checked-out state for extended
periods of time.  In fact, it would be unusual for it to be checked-in
other than during the baseline snapshot.

> Note that Greg and Edgar are making a different argument:
> they agree that the state of the version-controlled configuration
> is the state of the configuration rooted at the baseline-
> controlled collection,

We all agree.

> but they argue that protocol should
> be changed to say that the baseline-controlled collection
> should not be modifiable while version-controlled configuration
> is checked in (the protocol currently makes no such requirement).
> I'll respond to that in a separate message.

I understand their position, but if we believe that the version-controlled
configuration resource is a 'proxy' for operations on the configuration
(rather than _being_ the resources in the configuration), it is
unneccessary for it to be a version-controlled resource at all.  Maybe it
should not be checked-out or checked-in, but subject to some other method
that means 'take a baseline shapshot'.  Could be BASELINE, or whatever.

Tim
Received on Wednesday, 11 April 2001 09:39:01 GMT

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