Modeling data

The uToDoTypes unit is where we can add data types that are shared between the user interface and the data access module. To achieve a proper level of separation between the user interface and the data access logic, we should define the interface for communication between the two tiers of the application. The data module will implement it and the main form of the application should use this interface as the only way to communicate with the data module. In this way, we have a truly pluggable architecture. The user interface can be developed independently and we can provide different implementations of data access logic without affecting the rest of the application. Our data-driven app could be using different types of embedded databases, a different data access framework, or maybe we would want later to switch to storing our data in a plain file or in cloud storage...