You can represent the dynamic behavior associated with a system entity using a State Diagram.
The state diagram depicts the behavior of the system over time. This diagram relates the events received by the system to the states that the system can be in. When an event is received, the next state the entity enters depends on the current state, as well as the event. The change of state of a system is called a transition. Each transition is labeled with the name of the event that causes it.
Diagrams can be nested to show a particular state in more detail.
To create a system state transition diagram
1 Create a new state diagram.
2 Add symbols to the diagram to depict the behavior of the system.
System Transition: A transition signifies when an object moves from one state to another state when a specified event occurs.
System Synch State: A synch state is used for synchronizing concurrent regions of a superstate. It is used in conjunction with forks and joins to insure that one region leaves a particular state or states before another region can enter a particular state or states.
System Synch Bar: The Synchronization Bar is used to model the splitting or joining of transitions to or from concurrent states in a State diagram or Activity diagram.
System State: A state symbol represents a state that an object is in at a particular time. While in the state, the object satisfies some condition, performs some action, or waits for some event.
System Initial State: The initial state symbol is represented by a large black circle. Its label usually contains initial conditions. A transition line is drawn from the initial state symbol to the next state.
System Final State: The final state symbol’s label generally indicates final conditions. You can draw transition lines to it from more than one previous state.
System Dynamic Choice Point: Used to model the fact that one transition path is taken from a choice of many.
For each symbol that is created assigns system nodes and system entities to serve as keys for all states related to this diagram.