[egenix-users] Re: [Zope-DB] RFC: mxODBCZopeDA & ZEO

Charlie Clark charlie at egenix.com
Wed May 26 20:39:57 CEST 2004


On 2004-05-25 at 18:38:19 [+0200], Chris Withers <chris at simplistix.co.uk> 
wrote:
> Network shares, Subversion, etc...
> 
> Myself? I setup a whole instance in Subversion and check it out onto any 
> machien
> I want a client one...

Interesting. I assume this involves using some kind of file storage?

> >>>3) heterogeneous clients may in some circumstances confuse each other
> >>>configuration
> >>
> >>How?
> > 
> > take the mxODBCZopeDA for example: if a connection is configured to talk 
> > to
> > DSN=Chris or use a specific driver then this may not on all clients.
> 
> Ooo... ouch, yeah. Sounds like a system architecture problem. This is part 
> of
> cluster "being hard". Generally, having homogeneous nodes in a cluster is 
> the
> way to go, in which case the situation you describe shouldn't apply...

Yes, wasn't possible in the test configuration but maybe useful for support 
enquiries. Non-heterogeneous clients are likely to cause problems in 
load-balancing anyway.
 
> > This is an RFC targetted at those with real-life ZEO installations with
> > RDBMS. The example you cite is one where I think it might make more sense 
> > to
> > have a single connection
> 
> explain what you mean by connection.

>From website to cluster. The current state sets up identical copies of the 
connection object in the various ZEO clients. They have to communicate 
through a local ODBC manager with the database. In a sense this goes against 
something like the mxODBCZopeDA which should be able to handle all necessary 
connections from all ZEO clients in a single object. This looks like it's 
going to remain a theoretical difference as there is unlikely to be any 
performance difference either way.

We're essentially looking at the question: what does ZEO give you and how 
does it work?

However, it looks like the common setup avoids the pitfalls of separate 
physical installations.
 
> > talking to several clients which do the rendering.
> 
> explain what you mean by client.

ZEO-client
 
> > But we don't really know how much ZEO is out there and how much of it uses
> > Zope-DAs. We know that the mxODBCZopeDA works with ZEO but maybe it could
> > work better.
> 
> explain what you mean by "works with zeo"
> 
> And there's PLENTY of ZEO out there ;-)

That's good to hear. There doesn't seem to be much running with the 
mxODBCZopeDA which seems to suggest that such sites primarily use the ZODB 
for storage.

Charlie



More information about the egenix-users mailing list