live_controller.rb

class LiveController < ApplicationController
  include ActionController::Live

  def stream
    # Set the response header to keep client open
    response.headers['Content-Type'] = 'text/event-stream'

    begin
      100.times {
        response.stream.write("The temperature is #{ 100*rand} degrees\n")
        sleep 0.5
      }

      response.stream.write("That's all for now!")
    rescue IOError
      # client disconnected
    ensure
      response.stream.close
    end
  end
end