A functional decomposition modeling for switching software

We present, in this paper, a specification description method which can describe the concepts of concurrent tasks, abstractions, and finite state machines to represent the behavioral aspects of switching software systems. The hierarchical functional decomposition modeling method emphasizes the decomposition of a real-time system into concurrent tasks and defines the interfaces between these tasks. The hierarchical functional decomposition modeling approach has some strengths. The first one is that the use of data flow and control flow diagrams can assist in understanding the system. Second, it emphasises the use of state transition diagrams, particularly important in the design of real-time systems.