Detailed State Charts

The following shows a description of a detailed State Chart.

Figure 5.3: Example of a detailed state model

In a detailed State Chart:

• Transitions are simple. Each includes a single event that can be: a system operation, an actor operation, a timeout or a guard condition.
• States describe situations in which the system and environment may be at some point in time.

  A State situation is defined as a set of characteristic conditions.

  A characteristic condition is either a condition (i.e. a valuation of a domain entity) or a timeout condition.

  Two states are identical if they have the same characteristic conditions.

  States in the example are listed with their set of characteristic conditions. As an example, state 4 characteristic conditions are {Card is inserted, Alarm is System Status, status is irregular, PMSystem is ON}.

  Notice that all domain entities always have a value that may be explicit or unknown, in a given state. As an example, since attribute Display of the PMSystem doesn't have an explicitly defined value in state 4, its implicit value is unknown value.

  A timeout condition reflects the 'relevancy' of the fact that a timer expired. As an example, timeout condition Timer0:20 second that characterizes state 5 means that timer Timer0 that was set for 20 seconds has expired, and that information is 'relevant'.

  A state $s_{b}$ is a sub-state of a state $s_{a}$ (its super-state), if its characteristic conditions include those of $s_{a}$ in the logical sense. As an example, state 1 in the state model is a super-state of state 2. State 2 characteristic conditions include state 1 characteristic conditions.

  A state may have more than one direct super-states. State 17 which direct super-states are states 9 and 16 is an example of such a state.

• A transition specifies the change from a state (a starting situation) to another state (a resulting situation).