The DataStorage class must have a factory method that returns a concrete MetricsDAO (#60).
Because there are already implementations of backends that don't support metrics yet, the default implementation must return a DAO that always return no metrics but that behaves as a normal MetricsDAO object for read operations (there are no write operations yet).
The
DataStorageclass must have a factory method that returns a concreteMetricsDAO(#60).Because there are already implementations of backends that don't support metrics yet, the default implementation must return a DAO that always return no metrics but that behaves as a normal MetricsDAO object for read operations (there are no write operations yet).