stephensong / asyncmachine Goto Github PK

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.

npm i asyncmachine

• 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

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

• Edit on RunKit
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import { machine } from 'asyncmachine'
// define
const state = {
  // state Wet when activated, requires state Water to be active
  Wet: {
    require: ['Water']
  },
  // state Dry when activated, will drop (de-activate) state Wet
  Dry: {
    drop: ['Wet']
  },
  // state Water when activated, will add (activate) state Wet and
  // drop (de-activate) state Dry
  Water: {
    add: ['Wet'],
    drop: ['Dry']
  }
}
// initialize
const example = machine(state)
// initially the machine has no active states
example.is() // -> []
// activate state Dry
example.add('Dry')
example.is() // -> [ 'Dry' ]
// activate state Water, which will resolve the relations:
// 1. Water activates Wet
// 2. Wet requires Water
// 3. Dry de-activates Wet
// 4. Water de-activates Dry
// 5. Water activates Wet
example.add('Water')
example.is() // -> [ 'Wet', 'Water' ]

Presents how the state negotiation works.

• Edit on RunKit
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• Source on GitHub

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

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• Source on GitHub

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

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

Shows how pipes forward states between machines.

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

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

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

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

• Edit on Stackblitz
• Source on GitHub

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

• Comming soon!

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

• Inspect on StackBlitz
• Source on GitHub

For a real world example check TaskBot - a real-time sync engine for Google APIs.

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

MIT