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This guide walks through the flow of creating an actor system, spawning an actor, and sending messages. For the full ActorSystem API and configuration, see Actor System.

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Flow

  1. Create an actor system with NewActorSystem and Start
  2. Spawn an actor with Spawn(ctx, name, actor) → receive a *PID
  3. Send messages with NoSender().Tell (fire-and-forget) or NoSender().Ask (request-response)
  4. Shutdown with Stop when the application exits

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Actor interface

Implement the Actor interface to define your actor. See Actor Model for the full interface and method explanations.

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Messaging from outside

From outside the actor system (e.g., main), use NoSender() to send:
  • Tell — Fire-and-forget. No response expected.
  • Ask — Request-response. Blocks until reply or timeout. The actor must call ctx.Response(resp) to complete the request.

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Replying from an actor

When handling a message sent via Ask, call ctx.Response(resp) exactly once. The caller receives that value. For Tell, no reply is expected.

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ReceiveContext

Inside Receive, ctx provides:
MethodPurpose
Message()The message being processed
Sender()PID of the sender (nil for scheduled or system messages)
Self()PID of the current actor
Tell(to, msg)Send fire-and-forget to another actor
Ask(to, msg, timeout)Send request-response
Response(resp)Reply to an Ask
Unhandled()Mark message as unhandled
For more examples, see the goakt-examples repository.