/**
  * singleton pattern
  *
  * @return PlentySoapClient
  */
 public static function getInstance()
 {
     if (!isset(self::$instance) || !self::$instance instanceof PlentySoapClient) {
         self::$instance = new PlentySoapClient();
     }
     return self::$instance;
 }
 public function onExceptionAction(Exception $e)
 {
     $this->getLogger()->crit("Exception : " . $e->getMessage());
     // TODO check on http 500
     /*
      * check if token is valid
      */
     if ($e->getMessage() === "Unauthorized Request - Invalid Token") {
         /*
          * token is not valid
          * 
          * so renew token
          */
         PlentySoapClient::getInstance()->updateToken();
     }
     if ($this->getRetryOnException() == true) {
         if ($this->retryCount < $this->getRetryOnExceptionCount()) {
             $this->retryCount++;
             sleep(2);
             $this->execute();
         }
     }
 }