Drawing decision nodes

Decision nodes show branching conditions. A decision node can have only one incoming flow and two or more outgoing flows. The outgoing flows are labeled with a distinct guard condition and no event trigger. A predefined guard, denoted [else], can be used for no more than one outgoing flow.

Procedure

  1. Click the DecisionNode button DecisionNode button.
  2. Click, or click-and-drag, in the diagram to position the decision node where you want it.
  3. Draw at least two actions that will become targets of the outgoing flows.
  4. Draw an incoming flow from the source action to the decision node.
  5. Draw and label the outgoing flows from the decision node to the target actions.

Results

The following diagram shows the following behavior: When the phone rings, if someone picks up on the other end, you can talk; otherwise, you must leave a message. The decision node represents the decision point. In other words, after the PhoneRings() operation, if SomeonePicksUp resolves to True, the Talk() operation is called. Otherwise, the LeaveMessage() operation is called.

Diagram showing decision nodes

Use the Display Options window to determine whether to display the name, label, or nothing for the decision node.


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