server.rb

#! /usr/bin/ruby
# redis server command
# /usr/local/bin/redis-server ~/.redis_conf &

# EM server command
# ./server.rb

require 'rubygems'
require "bundler/setup"

require 'eventmachine'
require 'em-websocket'
require 'em-hiredis'
require 'sinatra/base'
require 'thin'
require 'json'

@sockets = []

class DemoApp < Sinatra::Base
  get '/' do
    send_file File.join(settings.public_folder, 'index.html')
  end
end
  
EventMachine.run do
  EventMachine::WebSocket.start(:host => '0.0.0.0', :port => 8080) do |socket|
    socket.onopen do
      @sockets << socket
      @sockets.each{ |s| s.send( { :type => :Connect, :data => "#{@sockets.size} clients connected"}.to_json ) }
    end
    
    socket.onmessage do |mess|
      puts "Message received: #{mess}, sockets: #{@sockets.size}"
      # send to all sockets except the one that sent the message
      @sockets.each{ |s| next if s == socket; s.send( { :type => :Message, :data => mess }.to_json ) }
    end
    socket.onclose do
      @sockets.delete socket
      @sockets.each{ |s| s.send( { :type => :Connect, :data => "#{@sockets.size} clients connected"}.to_json ) }
    end
  end
  
  redis = EM::Hiredis::PubsubClient.new
  redis.connect
  
  redis.errback do |code|
    puts "Error code: #{code}"
  end
  
  redis.subscribe("change")
  redis.subscribe("chat").callback do # |type, channel, message|
    puts "Subscribed to chat and change channels"
  end
  
  redis.on(:message) do |channel, message|
    puts "message on #{channel}: #{message}"
    @sockets.each{ |s| s.send( { :type => channel, :data => message}.to_json ) }
  end

  puts ">> WebSocket server listening on 0.0.0.0:8080"
  
  Thin::Server.start DemoApp, '0.0.0.0', 4000, signals: false
end