cakephp http如何发送回响应

Question

public function xml_post_test() {

  $response = $http->get('http://localhost/tests/receive_xml', $xml_string);
  debug ($response->body);
}

public function receive_xml() {
  //send to xml_post_test
}

我是CakePHP的新手。在receive_xml中，接收XML字符串。如何发送回xml_post_test？