[Zope] Mixing ZEO and non-ZEO instances

[J Cameron Cooper]

>
>
>I'm putting together a system which will include multiple Zope instances,
>mostly independent, some not.  Some I want to run with a ZEO backend,
>others I want to use the local file system for storage management.  Has
>anyone had any experience putting together a multi-instance system where
>some instances use ZEO and others don't?
>  
>
If by this you mean several Zope installations running on the same 
machine, some using ZEO and some using FileStorage/DirectoryStorage, 
then it's not even close to a problem. Several (or even many) Zope 
instances will run alongside each other just fine, so long as you take 
care to distribute ports (and maybe IPs) uniquely. I do this all the 
time, and so do a lot of other people.

You can have separate full installations for each instance, or you can 
have them share the same "executables" by setting up a software_home and 
several instance_homes, each of which can be configured to do whatever 
you want with regards to storage, extra products, etc. (You cannot have 
multiple instances running with the same storage, however.)

If you're going to be dealing with these a lot, you should take a look 
at the zopectl script, which has some clever support for managing 
multiple instances.

You should also evaluate whether or not you really need to do this, 
because I suspect you can probably get the same thing done with one 
instance with a VHM and mounted storages, though you can't control 
installed products on a per-area basis this way. See

http://www.zope.org/Members/jim/ZODB/MountedDatabases
http://www.zope.org/Members/anthony/software/MountedFileStorage

and especially...
http://hathaway.freezope.org/Software/DBTab
http://hathaway.freezope.org/Software/Ape

          --jcc