AsyncMachine is a relational state machine made for declarative flow control. It supports multiple states simultaneously, executes methods based on a dependency graph and provides an event emitter.

It allows for easy:

• state management
• parallel tasks
• loose coupling
• resource allocation / disposal
• exception handling
• fault tolerance
• method cancellation

It supports forming a network of state machines and can also be used as a simple state management library. Gzipped code is 7.5kb.

Install

npm i asyncmachine

Documentation

• AsyncMachine - The Definitive Guide (wiki) PDF version (25 pages, 1.5mb)
• API docs (TypeScript)
  • machine() factory
  • AsyncMachine class
  • Transition class
  • List of emitted events
• Roadmap

Components:

• states
• transitions
• relations
• clocks
• pipes
• queues

Features:

• synchronous mutations
• negotiation
• cancellation
• automatic states
• exception handling
• visual inspector / debugger

Examples

Dry Wet

This basic examples makes use of: states, transitions, relations and synchronous mutations.

• Edit on RunKit
• Inspect on StackBlitz

import { machine } from 'asyncmachine'
// define
const state = {
  Wet: { require: ['Water'] },
  Dry: { drop: ['Wet'] },
  Water: { add: ['Wet'], drop: ['Dry'] }
}
// initialize
const example = machine(state)
// make changes
example.add('Dry')
example.add('Water')
// check the state
example.is() // -> [ 'Wet', 'Water' ]

Negotiation

Presents how the state negotiation works.

• Edit on RunKit
• Inspect on StackBlitz
• Source on GitHub

Async Dialog

Presents the following concepts: automatic states, synchronous mutations, delayed mutations and loose coupling.

• Edit on RunKit
• Inspect on StackBlitz
• Source on GitHub

Exception State

A simple fault tolerance (retrying) using the Exception state.

• Edit on RunKit
• Inspect on Stackblitz
• Source on GitHub

Piping

Shows how pipes forward states between machines.

• Edit on RunKit
• Inspect on Stackblitz
• Source on GitHub

Transitions

Shows various types of transition handlers and the way params get passed to them.

• Edit on RunKit
• Inspect on Stackblitz
• Source on GitHub

TodoMVC and React

Classic TodoMCV example using AsyncMachine as the controller and React as the view.

• Edit on Stackblitz
• Source on GitHub

State streams with RxJS

Observe state changes and navigate through specific paths with RxJS, then feed the result back as a state.

• Comming soon!

Restaurant

A complex example showing how to solve the producer / consumer problem using AsyncMachine.

• Inspect on StackBlitz
• Source on GitHub

GTD Bot

For a real world example check GTD Bot - a sync engine for Google APIs.

Use cases

• state management
• synchronizing async actions
• solving non-linear problems
• fault tolerance
• resource allocation / disposal
• avoiding race conditions
• thread pools
• sync engines

License

MIT