It is workload dependent. My general way of thinking about it is containing a unit of work. Sometimes that is a single process, others it is a bunch of things.

It is workload dependent. My general way of thinking about it is containing a unit of work. Sometimes that is a single process, others it is a bunch of things. Sometimes I may want to run a database separate from my application code, sometimes not. How do you scale it, how do you manage it, how will it get deployed, all questions that go into the answer of what should go into it.