Answer to Question 1
The user interface is the concrete realization of messages passed between the actors and the system. UI design must map messages, their parameters, and their return values into UI metaphors. Therefore, the discovery and the modeling of the application flow, discussed in the previous chapter, is essential to the correct design of the user interface. We should be aware, however, that the same flow and the same set of messages can translate into different user interfaces, depending on the designer or client preferences, the platform, the development tools, and so on.
Answer to Question 2
A