Some notations of UML for modeling state machines *** to be revised ***

As explained in more detail in the UML introduction by Alain Williams, one needs the following notations for modeling systems with state machine behavior:

• Class diagrams: for defining the active objects (state machines) and the exchanged messages (signals)
• Composite structure diagrams: for composite system structure containing several communicating state machines, and the interfaces (here are some examples: ex1, ex2, ex3)
• State Machine diagrams: for defining the dynamic behavior of the state machines

There a number of predefined data types that can be used for message parameters and local variables of state machines (see UML introduction, slides 26 through 31). SDL data types allows for type constructors to allow for user-defined data types.

For a more advanced reader, here are slides on UML Version 2 prepared by Bran Selic before 2007.