Switch

We use the Switch construct to model an exclusive or of branches in a Communication Model, which is shown as a state chart in Figure 5.11. This state chart has a combined state Switch, which has two regions. In each region a choice element is placed directly after the init state. This choice models the possibility that the corresponding nucleus should be executed or not depending on the internal state of one communication party. It is necessary to assign a specific communication party to the construct, which selects the nucleus to be executed by evaluating the corresponding conditions at run-time. Because the combined state for each nucleus is outside of the Switch state, it is only possible to enter and execute the sub state machine of one of the nuclei states. An additional constraint for the Switch relation is, that in all situations exactly one nucleus has to be executed. The number of nuclei is not limited to 2 by this definition.