Abracadabra Protocol

Chapter 10 introduces state transition tables and diagrams. The emphasis is on explaining the basic principles, in particular, the relationship to purely textual Focus specifications expressed in predicate logic. The examples have been carefully selected to illustrate certain features or properties, and they are therefore both tiny and relatively trivial. The graphical specification constructs introduced in Chapter 10 can of course, in principle, also be used to describe systems of a more realistic complexity. Making the specification of nontrivial components practical requires, however, additional constructs for specification in the large, for example, hierarchical state machines in the style of Statecharts [Har87], or the SDL [ITU93] features for decomposing graphical descriptions of state machines into a number of diagrams.