One of the greatest features of CDI is that you can provide two or more different implementations to the same bean. This is very useful if you wish to do one of the following:
- Handling client-specific business logic that is determined at runtime. For example, providing different payment mechanisms for a purchase transaction.
- Supporting different versions for different deployment scenarios. For example, providing an implementation that handles taxes in the USA, and another one for Europe.
- Easier management for test-driven development. For example, you can provide a primary implementation for production, and another mocked one for testing.
To do that, we should first rewrite our bean as an abstract element (abstract class or interface) and then we will be able to provide different implementations according to the basic OOP principles...
