README
The Actor Model for JavaScript
🚧 Work in progress! 🚧
XActor is an actor model implementation for JavaScript and TypeScript, heavily inspired by Akka. It represents the "actor model" parts of XState and can be used with or without XState.
Resources
Learn more about the Actor Model:
- The Actor Model in 10 Minutes
- 🎥 The Actor Model Explained
- What is the Actor Model and When Should You Use It?
- 📄 ACTORS: A Model of Concurrent Computation in Distributed Systems (Gul Agha)
- 📄 A Universal Modular ACTOR Formalism for Artificial Intelligence (Carl Hewitt et. al.
Installation
- With npm:
npm install xactor --save
- With Yarn:
yarn add xactor
Quick Start
import { createSystem, createBehavior } from 'xactor';
// Yes, I know, another trivial counter example
const counter = createBehavior(
(state, message, context) => {
if (message.type === 'add') {
context.log(`adding ${message.value}`);
return {
...state,
count: state.count + message.value,
};
}
return state;
},
{ count: 0 }
);
const counterSystem = createSystem(counter, 'counter');
counterSystem.subscribe(state => {
console.log(state);
});
counterSystem.send({ type: 'add', value: 3 });
// => [counter] adding 3
// => { count: 3 }
counterSystem.send({ type: 'add', value: 1 });
// => [counter] adding 1
// => { count: 4 }
API
createBehavior(reducer, initialState)
Creates a behavior that is represented by the reducer
and starts at the initialState
.
Arguments
reducer
- a reducer that takes 3 arguments (state
,message
,actorContext
) and should return the next state (tagged or not).initialState
- the initial state of the behavior.
Reducer Arguments
state
- the current untagged state.message
- the current message to be processed by the reducer.actorContext
- the actor context of the actor instance using this behavior.
Actor Context
The actor context is an object that includes contextual information about the current actor instance:
self
- theActorRef
reference to the own actorsystem
- the reference to the actor system that owns this actorlog
- function for logging messages that reference the actorspawn
- function to spawn an actorstop
- function to stop a spawned actorwatch
- function to watch an actor
Spawning Actors
Actors can be spawned via actorContext.spawn(behavior, name)
within a behavior reducer:
const createTodo = (content = "") => createBehavior((state, msg, ctx) => {
// ...
return state;
}, { content });
const todos = createBehavior((state, msg, ctx) => {
if (msg.type === 'todo.create') {
return {
...state,
todos: [
...state.todos,
ctx.spawn(createTodo(), 'some-unique-todo-id')
]
}
}
// ...
return state;
}, { todos: [] });
const todoSystem = createSystem(todos, 'todos');
todoSystem.send({ type: 'todo.create' });
Documentation still a work-in-progress! Please see the tests for now as examples.