event_machine_rails.rb

#config/initializers/websocket_handler.rb
EM.next_tick do
  @channel = EM::Channel.new

  #Simulate messages.
  EM::PeriodicTimer.new(3) do
    random_string = rand(100_000).to_s
    @channel.push random_string
  end

  EM::WebSocket.run(host: '0.0.0.0', port: 8080) do |ws|
    ws.onmessage do |data|
      ...
    end

    ws.onclose do
      ...
    end
  end
end