State Diagrams Pepper

Purpose Show behavior from the view of movement through different states. See how you can get to a certain state See how you can leave a certain state See all the actions that can be done while in a state

2 Lists : State and Stimulus EX: A course in a registration system State List Stimulus List Stimulus Description Create course Initializes the course Register students Happens inside the open state. Cancel the course Cancels an existing course but a record of the course existing remains. Tell students it cancels Delete a course Delete a mistakenly created course Fill a course Closes the course Notify about cancelation Happens inside the canceled state State Description Initialized Exists, but no details set up Open Ready for registration Canceled Closed Deleted

Course State Diagram Credit to : http://laser.inf.ethz.ch/2012/slides/Jacobson/UML%20Past%20Present%20and%20Future%20Part%202.pdf

Words on the Line: Trigger : an action Guard (inside []) : a condition Transitional behavior (after /) : a message or variable setting

Summary Start with states List of state and stimulus helps you think of all different states Some actions may happen inside states and not be stimulus for movement Draw rounded boxes for states Look at each stimulus to see if it gets an arrow from that state. Not an activity diagram