IBM
Contents Index Previous Next



State Chart Notation


The state chart notation used in the SDL Suite is a subset of the notations used in OMT (Object Modeling Technique) and UML (Unified Modeling Language).

A state chart model is suitable to use together with class and object models. The descriptions of the behavior of a class in a class diagram is collected into a state chart which describes the dynamic view of the model by means of states and transitions between states.

State

A state symbol describes the name of the class, state variables, and internal activities. Internal activities are taking place upon entering the state, while in the state and when exiting the state. Activities are described by specifying events and associated actions. Figure 12 shows a collapsed state and a state with events.

Figure 12 : A collapsed state symbol and a state symbol
with events

Transition

A transition symbol is an arrow which typically connects two state symbols. A transition is triggered by an event together with a condition, and a transition then executes an action; see Figure 13.

Figure 13 : The transition from state1 to state2 is triggered by the event
my_event and the condition that attr1 is less than attr2

Start and Termination Symbol

The start symbol denotes the starting point of a state machine described by a state chart and the termination symbol denotes the point of termination of a state machine. Figure 14 shows a simple state machine, describing the behavior of a door, including start and termination symbols.

Figure 14 : A simple state chart with a start symbol and a termination symbol

Substates

States may be refined into nested diagrams of sub-states, or hierarchical states. The state represents a simplification of more complex behavior expressed in the nested diagram.

Figure 15 : A state with substates


http://www.ibm.com/rational
Contents Index Previous Next