[Zope3-Users] Not shutting z3 program for maintenance

[hass]

Hello all,

I did some extensive Z3 2 year ago and now I am warming up to get into
the pool of z3 again.

I was wondering if there was any way in z3 not to shut the whole program
down when code maintenance is needed.
It wold be like having a simple instance run in the background which can
do the basics, and then other functionalities plug into it as different
z3 instances.
so when one needs to update the code in one part, it can only shut the
responsible program (instance) without shutting the whole web server.

I googled a bit and thought maybe by having multiple instances which
share a database through ZEO and apache's rewrite module to redirect
change the port based on the URL, I can bundle something up but that
doen't seem so elegant I suppose.
Is there a more standard way to do this?
What do z3 experts do when they have a big server with many logically
seperate functionalities and they want to update only one of them, plus
they don't want to have down time for the whole server.

Any help is greatly appreciated.
Hass