[Zope-dev] [Q] Pickle support for C wrapper and ZEO

[Dieter Maurer]

Ames Andreas (MPA/DF) wrote at 2004-4-22 11:07 +0200:
> ...
>The ODBC api is object-based and exhibits four object types:
>environment, connection, statement and descriptor objects each of
>which has a set of methods and properties.  Pickle-wise I'm not so
>concerned about persistence across shutdown/restart cycles (I think
>it's reasonable to re-create your ODBC environments, connections
>etc. after restart) but rather about consistency across ZEO-instances.

You mean ZEO client instances not ZEO (server) instances, don't you?

Why do you think your ODBC objects should be consistent across
ZEO clients?
I do not think that it is necessary as all your requests your
be independent which means all transactions inside a single
request which implied that connections need not to be shared.

>My lack of experience makes me ask here for expert advise.
>
>1)  Does the ZEO scenario demand some pickle support, e. g. to
>    use consitent environments/connections etc. across ZEO instances
>    or do I just misunderstand ZEO?

You probably misunderstand ZEO.

ZEO is a storage server that stores persistent objects (as pickles).
"Persistent" means "persistence across shutdown/restart".
Any object stored by ZEO must be picklable.

But, as you are not interested in "persistence across shutdown/restart"
for your ODBC objects, there is probably no need to store them
in ZEO.

>2)  If pickle support is a good idea:  What scope would you find
>    reasonable?  I. e. I can imagine that persistence of
>    environments/descriptors could be useful

Maybe...

>    while persistent
>    connections/statements could cause more trouble than they are
>    worth.

This is definitely true.

>As you can see the whole thing isn't very clear to me and so I'd
>appreciate your comments.

See how (other) database adapters handle these issues...

-- 
Dieter