In this section we take a look at some advanced techniques for specification and how they can be used.
We have already seen how to use state machines to specify control in UML. An example of a widely used state machine specification language is the SDL language[Roc82], which was developed by the communications industry for specifying communication protocols, telephone systems, and so forth. As illustrated in Figure 7.6, SDL specifications include states, actions, and both conditional and unconditional transitions between states. SDL is an event-oriented state machine model because transitions between states are caused by internal and external events.
Figure 7.6 The SDL ...