public function setConnectionString($connectionString) {
		if (!isset($connectionString) || !is_string($connectionString) || trim($connectionString) === "") {
			throw new FtpException(
				Yii::t('gftp', '{connectString} is not a valid connection string', [ 
					'connectString' => $connectionString
				])
			);
		}
		
		$this->close();
		$this->connectionString = $connectionString;
	}