A state diagram is an analysis tool that can be used when a system (or component of a system) passes through a series of discrete states during operation. Trivially, the ATM itself goes back and forth between two states - RUNNING and STOPPED. More interesting, though, is the series of states an individual Session goes through as it gets the customer's PIN and repeatedly gets transaction choices and performs them. A state diagram for a Session is given below. It would also be possible (and perhaps desirable) to construct similar diagrams for transactions. (Is an "exercise left for the student" lurking here?)
[ Intro ]
[ Requirements ]
[ Domain Objects ]
[ Use Cases ]
[ State Diagram ]
[ Interaction Diagram ]
[ CRC Cards ]
[ Class Diagram ]
[ Class Desc. Forms ]
[ Operation Desc. Forms ]
[ Code ]
[ Executable ]