This is related to a previous question, if not exactly the same!
It’s not such a simple question because the actor model of concurrency allows for many different types of applications to be built, from a stateful single-VM application (with a few separate actor classes) to a stateless cluster of thousands of instances of an actor class.
The core principles are the same however:
- Never expose an actor’s state
- Communicate solely via the passing of immutable messages