application_controller.rb

module Owner
  class Response
    def each
      10.times do |i|
        yield("entry #{i}\n")
        sleep 1
      end
    end
  end

end

class ApplicationController < ActionController::Base
  def index
    headers['Content-Type']              = 'text/plain'
    self.response_body = Owner::Response.new
  end
end

routes.rb

StreamingTest::Application.routes.draw do
  root :to => "application#index"
end