[Zope-dev] [Q] Pickle support for C wrapper and ZEO
Dieter Maurer
dieter at handshake.de
Thu Apr 22 19:29:39 EDT 2004
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
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