Action Cable

So I heard you want to make your Rails application realtime...

+ @HayleyCAnderson

Slides: http://hayleycanderson.github.io/action-cable-intro

First, Some Background

HTTP vs. WebSockets vs. Everything Else

HTTP = Hypertext Transfer Protocol

• GET, POST, DELETE, etc. are HTTP methods sent by clients
• A client sends a request, and the server sends a response

WebSockets

• Allows a bidirectional connection between client and server
• Both client and server can send and receive data in real time
• Created by HTTP connection being upgraded, then held open

Everything Else

• Short Polling - Client periodically sends repeated HTTP requests to the server
• Long Polling - Server holds open HTTP connections until new data is sent
• HTTP Streaming - Server holds open HTTP connection and sends data over one connection
• Server Sent Events - Client opens HTTP connection that can accept push notifications

Rails + Realtime

( Until Rails 5 = 💔 )

• ActionController::Streaming (sorry, wrong type of streaming)
• ActionController::Live + Server Sent Events
• Pusher, Faye, Node, etc.

But now, Action Cable

A fullstack WebSockets implementation built directly into Rails

• Create channels with classic Rails namespacing
• Broadcast data from anywhere within application
• Subscribe views to channels to pick up broadcasted data
• Retain flexibility but let Rails worry about connections

Let's see it in action!

( Demo )

So what's really behind the magic?

( The short version )

The Server

• Run separately or mounted as an engine
• Establishes pubsub connection (Redis or PostgreSQL)
• Creates an event loop that listens in the background

The Connection

• Client-side consumer creation initiates connection
• Consumer make a GET request to server and requests upgrade
• Server can authorize, identify, and/or accept connection

The Channel

• Channels are exposed to and called by the client
• Allows consumer subscription to actual pubsub channel
• Represents a stateless stream of data accessible to consumer

Questions?

+ @HayleyCAnderson

Slides: http://hayleycanderson.github.io/action-cable-intro

Resources

• Action Cable Demo
• Action Cable README
• Action Cable Examples
• Action Cable - Friend or Foe? by Nate Berkopec
• Rails 5 Preview: Action Cable Part I by Sophie DeBenedetto
• Using ReactJS with Rails Action Cable by Vipul