States' diagrams (statecharts)

The preceding states/scenarii can be grouped together to define the global behavior for a class (of objects).
This model must have an initial state (dot) and can have a final state.
A transition ...

• Must have an event such as operation call (message received) or a timing constraint (after(delay))
• Can be refined with a [guard] (i.e. a logical expression to fire the transition and change state)
• Can also have actions (e.g. operation call /object.message()) executed when the transition is activated.

Statechart (DrawerApps' behavior)

NB. A scenario is then simply a trace in the statechart.