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Re: client workspaces, merging and forking

From: Alison Macmillan <alison.macmillan@oracle.com>
Date: Tue, 04 Sep 2001 13:12:31 +0100
Message-ID: <3B94C52F.406ED951@oracle.com>
To: Tim Ellison <Tim_Ellison@uk.ibm.com>
CC: ietf-dav-versioning@w3.org


Tim Ellison wrote:

> "Clemm, Geoff" <gclemm@rational.com> wrote:
> >    From: Alison Macmillan [mailto:alison.macmillan@oracle.com]
> >
> >    > [to checkin a working resource whose DAV:checked-out version does
> not
> >    > match the DAV:checked-in version of the DAV:auto-update VCR]
> >    > Do what you would do on a non-forking server, i.e. checkout the new
> >    > version to get a new working resource, merge the contents of your
> old
> >    > working resource into that new working resource, delete the old
> >    > working resource, and then checkin the new working resource (and if
> >    > someone else has checked in a new version since your checkout,
> >    > repeat the process).
> >
> >    Or, could you also just merge from the DAV:checked-in version of the
> VCR
> > to
> >    the working resource, and then check in the working resource? (Now
> that a
> >    working resource can be a merge target).
> >
> > Not by the current protocol, since the DAV:no-overwrite-by-auto-update
> > postcondition states:
> >
> >  If the DAV:auto-update property for the checked-out resource
> >  identifies a version-controlled resource, the DAV:checked-out property
> >  of the checked-out resource MUST identify the same version as the
> >  DAV:checked-in property of that version-controlled resource.
> >
> > We could relax that constraint to say:
> >
> >  If the DAV:auto-update property for the checked-out resource
> >  identifies a version-controlled resource, at least one of the
> >  versions identified by the DAV:predecessor-set property of the
> >  checked-out resource MUST identify a version that is either the same
> >  as or a descendant of the version identified by the DAV:checked-in
> >  property of that version-controlled resource.
> >
> > If there are no objections, I'll place this on the "editorial fix"
> > list for draft 17.
>
> I object to this -- it is certainly not an editorial fix.
>
> The purpose of this postcondition is to prevent the auto-update overwriting
> changes made by other clients, by ensuring that the update is being applied
> to the same state of the resource that was checked-out.  With this proposed
> rewrite data can be lost unwittingly.
>

How are other client's changes overwritten? Doesn't the constraint on the value
of DAV:predecessor-set indicate that the appropriate merge has happened?

R'gds,
Alison.

--
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 The statements and opinions expressed here are my own
 and do not necessarily represent those of Oracle Corporation.
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Received on Tuesday, 4 September 2001 08:14:42 GMT

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