def __init__(self, cfg_db):
self.__logger = logging.getLogger(__class__.__name__)<EOL>cfg = na3x_cfg[NA3X_DB][cfg_db]<EOL>self.__connection = MongoClient(<EOL>'<STR_LIT>'.format(cfg[MongoDb.__CFG_PARAM_MONGO_USER], cfg[MongoDb.__CFG_PARAM_MONGO_PSWD],<EOL>cfg[MongoDb.__CFG_PARAM_MONGO_HOST],<EOL>cfg[MongoDb.__CFG_PARAM_MONGO_PORT]))[<EOL>cfg[MongoDb.__CFG_PARAM_MONGO_DBNAME]]<EOL>self.__logger.debug('<STR_LIT>'.format(cfg[MongoDb.__CFG_PARAM_MONGO_DBNAME]))<EOL>
Creates/take from pool MongoDB connection
:param cfg_db: db descriptor, db should be defined db.json configuration file