Core Concepts

1) Actor

Each actor implements the Actor trait.

• type Message: message type this actor accepts
• type Result: handler result type
• type Error: handler error type
• handle(&mut self, Arc<Self::Message>)

Each actor defines its own independent message type.

2) ActorSystem

ActorSystem manages actors by address (String).

• register: register(...)
• send: send::<T>(address, msg)
• request/response: send_and_recv::<T>(address, msg)
• broadcast: send_broadcast::<T>(regex, msg)
• job execution: run_job::<T>(...)

3) Type-Safety Model

Compile-Time Guarantees

send::<T>() accepts <T as Actor>::Message. Once T is chosen, the message type is fixed at compile time.

For example, send::<MyActor1>(..., MyMessage2::B(...)) does not compile.

Runtime Guarantees

Addresses are plain strings, so address-to-actor-type matching is validated at runtime.

• system stores actor_type with each address
• FindActor checks type equality
• mismatch returns runtime errors such as AddressNotFound or MessageTypeMismatch

In short:

• message type compatibility: compile time
• address mapping compatibility: runtime

4) Lifecycle and Failure Handling

Actor lifecycle states:

• Starting
• Receiving
• Stopping
• Terminated
• Restarting

On handler error, behavior depends on ErrorHandling:

• Resume: continue actor loop
• Restart: restart actor
• Stop: terminate actor