/**
  * setter for {@see $_backendType}
  * 
  * @todo persist in db
  * 
  * @param string $backendType
  * @return void
  */
 public static function setBackendType($backendType)
 {
     if (empty($backendType)) {
         throw new Tinebase_Exception_InvalidArgument('Backend type can not be empty!');
     }
     $newBackendType = ucfirst($backendType);
     if (Tinebase_Core::isLogLevel(Zend_Log::DEBUG)) {
         Tinebase_Core::getLogger()->debug(__METHOD__ . '::' . __LINE__ . ' Setting backend type to ' . $newBackendType);
     }
     self::$_backendType = $newBackendType;
 }