37 / 56
35
One Model, Many Interests, Many Views
Mapping for the State Transition Diagram
For the state transition diagram, child states are drawn as rounded rectangles. The lines between states
represent valid transition paths. Transitions are directional, exiting from one state and entering another.
While states may have multiple transitions, transitions are limited to a single entry and a single exit.
While transitions can be named and have properties, the focus is generally on the event that triggers
the transition and the corresponding conditions:
• Calling events are written in the form “EventName (condition)”, and the parentheses are
written even if the condition is empty;
• Signaling events are written in the form “EventName (condition)”, but the parentheses are
not written if the condition is empty;
• Events based upon a Boolean condition are written in the form “when (condition)”;
• Events based upon time are written in the form “at (condition)” if they occur at an absolute
time or “after (condition)” if they occur after a certain amount of time has passed;
• Any guard condition shown in square brackets.