[Zope3-dev] Tossing Data.fs considered harmful

[Tres Seaver]

On Mon, 2003-03-17 at 12:49, Jeremy Hylton wrote:
> On Sat, 2003-03-15 at 16:19, Tres Seaver wrote:
> > Jeremy's note about the opaque pickles said, "If this is going to cause
> > anyone heartache, please let us know ASAP."  I did not construe that as
> > an offer to write a conversion script, but rather as an offer to
> > negotiate about when the branch would land.
> 
> It's all a question of negotiation.  Writing a conversion script is
> extra work for me.  If no one cares about tossing their Data.fs, then I
> don't want to waste time doing useless work.  Same goes for a minor
> inconvenience.  If anyone was going to suffer real hardship or
> heartache, then I would have written a conversion script.
> 
> It's relatively easy for Barry and I to handle migration issues.  Most
> of the time we've just got to manipulate a bunch of opaque pickles.  At
> worst, we sniff a few of them.  I expect we could even write a
> conversion script from ZODB3 databases to ZODB4 databases without too
> much hassle.  But the cost of writing conversion scripts for each
> incremental change adds up.
> 
> I think people reorganizing higher level services will have more
> trouble.  They've actually got to worry about the contents of the
> pickles -- relationships among objects, removed and renamed classes,
> etc.
> 
> I wonder if a reasonable middle ground is to offer conversion utilities
> between each milestone release.  Each time we release version N+1, we
> provide an upgrade script that deals with data from version N.  If
> someone wants to develop applications on top of Zope, they ned to stick
> to milestone releases.

I buy that completely.  For such a plan to be workable, we are going to
need to be clear about the schedule for such releases, and work to keep
them do-able with some predictable frequency.  For instance, we may need
to move to packaging different portions of the Zope3x tree sepearately: 
I am (obviously) likely to need stability in ZODB, which my application
will not likely stress much;  I may be "pushing the envelope" on other
pieces (workflow, for instance).  Your release today of ZODB 4a is a
fine start in that direction.

Best,

Tres.
-- 
===============================================================
Tres Seaver                                tseaver@zope.com
Zope Corporation      "Zope Dealers"       http://www.zope.com