Building the pieces

Okay, you know the model is responsible for maintaining all the data, state and any application logic. So what’s the BeatModel got in it? Its main job is managing the beat, so it has state that maintains the current beats per minute and lots of code that generates MIDI events to create the beat that we hear. It also exposes an interface that lets the controller manipulate the beat and lets the view and controller obtain the model’s state. Also, don’t forget that the model uses the Observer Pattern, so we also need some methods to let objects register as observers and send out notifications.