In this chapter you implemented the user registration feature. Let's take a moment to examine how Cairngorm was used in implementing this feature.
You created ChangeMainViewEvent and ChangeMainViewCommand classes, which enable you to navigate to the main views of the application. These classes use constants to correspond to the main views so that they are more flexible in case you decide to change how the main view operates.
You created RegisterUserEvent, RegisterUserCommand, and RegisterUserDelegate classes, all of which make use of a UserVO class to pass data so that an account can be created.
You created a UserNotificationVO class that enables you to display different types of messages to the user by indicating a message type.