Creating a production buildout

We would be remiss at this point if we did not discuss adding Zope Enterprise Objects (ZEOs) to our buildout. ZEO provides a way to allow numerous Zope 2 instances to access the same database (Data.fs file).

During a normal operation (that is, without ZEO), Zope 2 locks the Data.fs file when it is in use. When ZEO is in use, it locks the file too, but allows connections over TCP/IP.

So from now on, we will be using ZEO. This will enable us to do a number of things:

• Learn how to use ZEO

• Establish additional connections to the database to facilitate

  • Backups

  • Debugging

  • Database packing

  • Load balancing

However, if we were to add ZEO to our current buildout, we would experience this problem:

$ bin/buildout -c 05-deployment-maintenance-production.cfg  
Updating zope2. 
Updating fake eggs 
Updating instance. 
Installing plonesite. 
2010-05-19 22:27:32 WARNING ZEO.zrpc (10025) CW: error connecting to ('127.0.0.1', 8100): ECONNREFUSED

This is because in 05-deployment-maintenance...