public static function get($config = null) {
		if (!isset($config['driver'])) {
			throw new ConnectionException("Unknown driver");
		}
		if (!isset($config['host']) || !isset($config['port'])) {
			throw new ConnectionException("Host and Port is required");
		}
		$type = $config['driver'];
		$hash = md5($type . ':' . $config['host'] . ':' . $config['port']);
		if (!isset(self::$created_driver[$hash])) {
			if (isset(self::$driver[$type])) {
				$className = self::$driver[$type];
			} else {
				$className = __NAMESPACE__ . '\\Driver\\' . ucfirst($type);
			}
			self::$created_driver[$hash] = new $className($config);
		}
		return self::$created_driver[$hash];
	}