POOP / Python (Object Oriented Persistence) ?

[Martijn Faassen]

"Tony J Ibbs (Tibs)" <tony at lsl.co.uk> wrote:
[snip]
> Being able to rely on objects still being around at the next invocation of a
> program without the programmer having to (seem to) take any special action
> can make certain types of application rather quicker to write ("certain
> types" including things like GIS, for instance).

[snip]
> If that's what's being talked about, it's a bit beyond just having *Pickle
> around (and if it's not what's being talked about, that's a pity), and I
> think Zope, etc., aren't quite talking about the same thing either.

In fact, I do think the Zope Object Database (ZODB) does this. The only
real thing you need to take care of is mutable attributes; you need
to treat those as immutables or explicitly call the transaction. Everything
else is transparent as long as you derive your object from Persistent.

> [One of the other exciting aspects of the Glasgow efforts is/was that they
> were also looking carefully at the problems of versioning

The ZODB has this; it could be improved but right you can change the ZODB from
one point of view, keeping it the same from others. It also has undo
facilities allowing you to undo transactions back in time.

> multi-user access,

The ZODB obviously can do this; multi-threaded access to the object database
exists.

> persistence over LARGE networks, etc.

What would this mean? Looks like ZODB can't do this; what is in the works
though is ZEO, which allows one to cluster object databases; there's still
a single object database but different servers may mirror it; any changes
to one will be paralleled by changes in others.

Another topic in Zope that I haven't looked a lot at is mountable databases,
allowing one to connect a number of ZODBs with different properties together.

> - all the real problems one would get if one actually *used* the stuff]

Right, and since us Zope folks are using the stuff, some of these problems
seem to be taken care of. Do you still think what the ZODB does is much
different from what you're describing?

Regards,

Martijn
-- 
History of the 20th Century: WW1, WW2, WW3?
No, WWW -- Could we be going in the right direction?