Actors

Learn how to use actors and the actor model in XState and Stately Studio.

• Actors

  When you run a state machine, it becomes an actor: a running process that can receive events, send events and change its behavior based on the events it receives, which can cause effects outside of the actor.

• State machine actors

  State machine actors are actors whose logic is represented by a finite state machine or statechart.

• Promise actors

  Promise actors are actors that represent a promise that performs some asynchronous task. They may resolve with some output, or reject with an error.

• Transition Actors

  Transition actors are actors whose logic is represented by a state-transition function, which is a function that returns the next state of an actor given:

• Callback Actors

  Callback actors are actors whose logic is represented by a function that can "callback" to the parent actor by sending events (via sendBack(...)). It can also receive(...) events from other actors.

• Observable Actors

  Observable actors are actors that represent an observable stream of values. This makes it easy to interop with observable libraries like RxJS.

• Invoke

  State machines can “invoke” one or many actors within a given state. The invoked actor will start when the state is entered, and stop when the state is exited. Any XState actor can be invoked, including simple Promise-based actors, or even complex machine-based actors.

• Spawn

  You can use spawn to run actors. Actors created with spawn are spawning actors, and actors created with invoke are invoking actors.

• Systems

  An actor system is a collection of actors that can communicate with each other. Actors can invoke/spawn other actors, which forms a natural hierarchy of actors that belong to the same system.

• Inspection

  The Inspect API is a way to inspect the state transitions of your state machines and every aspect of actors in an actor system. Including: