Section 3.9. Starting an Activity

3.9. Starting an Activity

The simplest and most common way to start an activity is with a single initial node; most of the diagrams you've seen so far in this chapter use this notation. There are other ways to represent the start of an activity that have special meanings:

• The activity starts by receiving input data, shown previously in "Showing Input to and Output from an Activity."

• The activity starts in response to a time event, shown previously in "Time Events."

• The activity starts as a result of being woken up by a signal.

To specify that an activity starts as a result of being woken up by a signal, use a receive signal node instead of an initial node. Inside the receive signal, node you specify what type of event starts the activity. Figure 3-21 shows an activity starts upon receipt of an order.