worker.rb

class PuSHCallback < EM::Connection
  include EM::HttpServer

  def post_init
    puts Time.now.to_s + "> New callback initialized"
  end

  def process_http_request
    response = EM::DelegatedHttpResponse.new(self)
    puts Time.now.to_s + "> Verify requset from " + @http_request_uri
    response.status = 200
    response.content_type = "text/html"
    response.content = @http_request_query_string["hub.challenge"]
    response.send_response
  end

end

EM.run {
  EM.start_server "0.0.0.0", 8082, PuSHCallback
}