WebSocket Rack

Rack-based WebSocket server

Create sample rack config file, and inside build app basing on Rack::WebSocket::Application.

require 'rack/websocket'

class MyApp < Rack::WebSocket::Application
end

map '/' do
  run MyApp.new
end

After that just run Rack config from Rack server:

thin -R config.ru start

Done.

Rack::WebSocket::Application make following methods available:

Called once after server is started. This is place for application configuration so each instance variables from here will be available in whole application.

Example:

class MyApp < Rack::WebSocket::Application
  def initialize(options = {})
    super
    @myvar = 4
  end
end

It is important to include 'super' in initialize function, so application will be properly configured.

Please notice that in some servers, when 'initialize' is called, EventMachine reactor is not running yet. If you would like to configure EventMachine-based software, then you need to put it inside 'EM.next_tick' block, so this function will be called in first cycle of reactor.

Example:

class MyWebSocket < Rack::WebSocket::Application
  def initialize
    EM.next_tick { @redis = EM::Hiredis.connect }
  end
end

Called after client is connected. Rack env of client is passed as attribute.

Example:

class MyApp < Rack::WebSocket::Application
  def on_open(env)
    puts "Client connected"
  end
end

Called after client is disconnected. Rack env of client is passed as attribute.

Example:

class MyApp < Rack::WebSocket::Application
  def on_close(env)
    puts "Client disconnected"
  end
end

Called after server receive message. Rack env of client is passed as attribute.

Example:

class MyApp < Rack::WebSocket::Application
  def on_message(env, msg)
    puts "Received message: " + msg
  end
end

Called after server catch error. Variable passed is instance of Ruby Exception class.

Example:

class MyApp < Rack::WebSocket::Application
  def on_error(env, error)
    puts "Error occured: " + error.message
  end
end

Sends data do client.

Example:

class MyApp < Rack::WebSocket::Application
  def on_open(env)
    send_data "Hello to you!"
  end
end

Closes connection.

Example:

class MyApp < Rack::WebSocket::Application
  def on_open(env)
    close_websocket if env['REQUEST_PATH'] != '/websocket'
  end
end

Options passed to app on initialize.

Example:

# In config.ru
map '/' do
  run MyApp.new :some => :variable
end

# In application instance
@options # => { :some => :variable }

Currently we support drafts -75 and -76 form old(hixie) numeration and all drafts from -00 to -13 from current(ietf-hybi) numeration. Please note that ietf-hybi-13 is currently proposed as final standard.

Currently we are supporting following servers:

• Thin

Just use :backend => { :debug => true } option when initializing your app.

Thin v1.2.8 has an --ssl option - just use that! :)

Check Thin config - any option supported by Thin(like demonizing, SSL etc.) is supported by WebSocket-Rack.

Author: Bernard Potocki

Released under MIT license.

If you like my work then consider supporting me: