WebSockets for Ruby made easy

Easy WebSockets + Powerful Publish / Subscribe

Iodine (with or without Plezi) offers easy WebSockets and a powerful pub/sub solution for Ruby.

Add iodine to your favorite Framework or use it directly for a Rack application:

require "iodine" # this config.ru example runs on iodine.

# A simple Websocket Callback Object.
module BroadcastClient
  # subscribe to new clients.
  def self.on_open client
    client.subscribe :broadcast
  # send a message, letting the client know the server is shutting down.
  def self.on_shutdown client
    client.write "Server shutting down. Goodbye."
  # broadcast incoming messages to chat
  def self.on_message client, data
    client.publish :broadcast, data

# A simple router - Checks for Websocket Upgrade and answers HTTP.
    { 'Content-Type' => 'text/html', 'Content-Length' => '32' },
    ['Please connect using websockets.'] ]
  WS_RESPONSE = [0, {}, []].freeze
  # this is function will be called by the Rack server (iodine) for every request.
  def self.call env
    # check if this is an upgrade request.
    if(env['rack.upgrade?'.freeze] == :websocket)
     env['rack.upgrade'.freeze] = BroadcastClient
     return WS_RESPONSE
    # simply return the RESPONSE object, no matter what request was received.
# run this example rack app.

Running Fast : plezi => iodine

The Plezi framework started out as an abstraction layer that used socket hijacking to make WebSockets for easy and seamless.

However, using the regular Ruby servers had a high performance penalty for a number of reasons - which is how iodine was born.

Performance issues were solved by unifying the IO engine for both HTTP and WebSockets and linking it together with the Pub/Sub registry within a new type of Ruby server - iodine.

Now everything can easily be done directly by using the optimized iodine server.

How to install?

Simply install the iodine gem.

gem install iodine

What about the Plezi gem?

As plezi evolved performance became critical, functionality moved from the framework directly into the iodine server. At this point the plezi gem should be considered a mere wrapper around iodine.