borland Packages Class Hierarchy dx.dataset Package
com.borland.dx.dataset.Designable +----com.borland.dx.dataset.DataModule
The data module also provides a centralized location where "business logic" can be stored. "Business logic" describes the rules by which data is manipulated before and after the user (or client) sees the data. Business logic may include default values, filter criterion, constraints on data insertions, and so on. By encapsulating such logic in a single location, you are assured that every application that uses your data module provides consistent business logic.
The DataModule interface does not contain any variables, properties, methods, or events, however, by implementing this interface, you implicitly declare that your class is a data module.
When referencing your data module in your application, you can access a single instance of your data module shared across your application instead of allocating memory for multiple instances. To do this, your custom data module class should define a public static method that retrieves the current instantiation of the data module. This same method should also create and return a new instantiation if one doesn't already exist. For an example of this code, use the Data Module wizard to create a data module and examine the logic of the code it generates.