I was passing in an object, oHandler, to another object, oxServer, but decided I want to create oHandler inside oxServer instead, to keep everything encapsulated so references are easier to make. What decides when to use NewObject, CreateObject or AddObject? I was using CreateObject for oHandler, then passing it in, but what's the correct way to do it inside oxServer? Why?

As a generally rule, I use Composition ( AddObject ) rather than Aggregation ( NewObject or CreateObject ) whenever possible because the container object "owns" all of the contained items. When the container is destroyed, all of its contained objects are destroyed too. So the chances of a dangling reference are greatly reduced.