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pcplantdb - [pcplantdb] technical details, plan, re: synthesis

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  • From: Chad Knepp <pyg@galatea.org>
  • To: pcplantdb@lists.ibiblio.org
  • Subject: [pcplantdb] technical details, plan, re: synthesis
  • Date: Mon, 2 Aug 2004 15:55:32 -0500

Nature and fate decided to cut lose during the last 18 hours;
seemingly plotting against me. Last night shortly after I responded
to *la vision* and was composing a zope report, the inverter in the
building that doubles as my office fried a circut board dumping my
work. The local electrical gurus/geeks are puzzled as to the problem
and it will be at least a week before it comes back on line. Then it
decided to rain... 6+ inches later with flash flooding occuring all
over the county I am reinstated in a different (actually better)
location and will work from here until the inverter situation is
repaired. Anyway...

So I'm just going to summarize the stuff I wrote earlier.

o We need to settle on a platform. I would like to use Zope 2.7.2,
the latest stable version and python 2.3.4 (or 2.3.3). More below.

o John H.: Can we start with your box, at least until things get
more settled? If so, can we use the above versions? If you are
short on time or don't want to mess with differing global versions,
I can (w/shell access) do a local install and run it nohup on a high
port so the group can play with it. I can also be talked into
different versions with convincing arguments.

o ZODB rocks my world and is amazingly simple. ZEO is also
incredibly cool and I can see a lot of possibilities esp. offloading
server effort to high bandwidth clients. It also would fulfil my
dreams about HG being a peer-to-peer distributed database... also
allowing enduser private data like garden logs that tie in
seamlessly. This is all very future stuff, but I feel pretty
excited about the potentials of the Zope platform.

o Zcatalog is for Zope objects. This still may be what we want, but
I really haven't spent much time looking at Zope itself. There is a
package for ZODB called IndexedCatalog
<http://async.com.br/projects/IndexedCatalog/> which should provide
the needed functionality independent of Zope. I don't know what we
will end up using but I do think that we have the tools in the Zope
package to do the job.

o ZODB does not have the built in capability to track individual
user edits infinitely. It has ACID style transactions with undo
(depending on storage type) just like any good RDBMS, but this is
for consistency and needs to be purged frequently or the database
will die of bloat... plus rollbacks can't happen on something that's
changed twice. In summary, unless we commit to programming a system
of tracking everything every user does (fairly complex), we should
go with the simpler method of adding an author credit to objects
that given authors add/modify.

o Schema is more important to ZODB than I initially thought in the
sense that when you have a working version and you add an attribute
to an object only the newly created objects will have the complete
set of attributes. In order to update the schema in
preexisting/working objects you need to write custom scripts to
traverse the objects in the database and add the attributes to them.
In some situations finding (being able to traverse) all of the
changed objects can be tricky. I don't forsee that we will have too
many objects inside of objects that need to be changed so I don't
think this will be a big deal. It probably won't be as hard as
making the changes in an RDBMS and then changing your engine code
and SQL. Mostly this is a note to myself.

Plan realated stuff:

So nobody really responded to my emails regarding the fact that 1) I
need additional time to learn Zope and 2) I really only can commit to
30 hours a week. This definitely puts a skew on the Project Plan, and
I'd like some feedback. According to the plan I am scheduled to
complete around 200 hours of work by the end of August. Granted, my
estimates are high estimates but I think it is unreasonably optimistic
to assume that the current Project Plan will not be at least two weeks
late by Sept 1. Not sure where to go with this.

I've cleared up a lot of time to focus on HG during August and
here is what I think is quite possible over the next two weeks.

Aug 2-4 Finish demo accounting/budgeting app. in ZODB w/CLI
Aug 5-7 Create a Zope front end for app (to learn Zope)
Aug 8-12 Start and finish 1 of my plan (Week 2 of Project Plan)
Aug 13-14 Get it running somewhere/somehow

Steph writes:
> hello again everybody,
>
> So it


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