Section 10.1. The Parts of an Interaction Overview Diagram

10.1. The Parts of an Interaction Overview Diagram

The best way to understand a interaction overview diagram notation is to think of it as an activity diagram, except instead of an action, a complete interaction is described by using its own diagram, as shown in Figure 10-1.

Any number of participants may be involved in the interactions that occur within the overview. To see which participants are involved across the entire overview, a lifelines subtitle is added to the diagram title, as shown in Figure 10-2.

Figure 10-1. Individual interactions are placed on an interaction overview diagram as though they were actions on an activity diagram

Figure 10-2. The lifelines subtitle shows the combined list of participants involved in the interactions within the overview

Similar to an activity diagram, the interaction overview begins with an initial node and ends with a final node. Control flows between these two nodes and passes through each of the interactions in between. However, you are limited not to just a simple sequential flow between the interactions.

Just as control flow on an activity diagram can be subjected to decisions, parallel actions, and even loops, so can the control flow on an interaction diagram, as shown in Figure 10-3.