WebSocket Rack

Rack-based WebSocket server

Usage

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.

Configuration

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

initialize

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

on_open(env)

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

Example:

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

on_close(env)

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

Example:

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

on_message(env, msg)

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

on_error(env, error)

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

send_data(data)

Sends data do client.

Example:

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

close_websocket

Closes connection.

Example:

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

Available variables:

@options

Options passed to app on initialize.

Example:

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

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

FAQ

Which WebSocket drafts are supported:

Currently we support drafts -75 and -76 form old(hixie) numeration and all drafts from -00 to -08 from current(ietf-hybi) numeration.

Which Rack servers are supported?

Currently we are supporting following servers:

  • Thin

How to enable debugging?

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

How to enable wss/SSL support?

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

How to use function xxx?

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

Why (using Thin) user is disconnected after 30 seconds?

This is bug in EventMachine < 1.0.0. Please consider updating to newer version or use thin-websocket wrapper around thin binary.

About

Author: Bernard Potocki <bernard.potocki@imanel.org>

Released under MIT license.