Presentation layer objects

The presentation layer should be located behind interfaces that handle both presentation and reception. The main reason is that if you have two interfaces, one for the view and the other that receives it, you could theoretically end up with two different objects assigned to each causing weirdness in testing.

However, if your interface evolves into dozens of methods, you might want to step back and see how to divide it into smaller units and then combine them. Not necessarily based on getting and presenting, but more logical sections of your presentation UI.

For example, you might have an IPresentationUI with two variables, one is the IPresentationDisplay interface and the other is the IPresentationControl. The only registration procedure you have will accept an IPresentationUI object. A class that implements the Prensentation layer will implement three interfaces: IPresentationUI, IPresentationControl, and IPresentationDisplay.