/**
  * This overwrites the default authenticate method in sdk.class.php to address SQS queue URLs.
  *
  * @return CFResponse Object containing a parsed HTTP response.
  */
 public function authenticate($operation, $payload)
 {
     // Save the current hostname
     $hostname = $this->hostname;
     if (isset($payload['QueueUrl'])) {
         // Change the hostname to the queue URL
         $this->hostname = $payload['QueueUrl'];
         // Remove "QueueURL" from the payload
         unset($payload['QueueUrl']);
     }
     // Perform the request
     $response = parent::authenticate($operation, $payload);
     // Restore the hostname
     $this->hostname = $hostname;
     return $response;
 }