Control Flow

An Action executes only when all of its Flows are available. In the case of a Data Flow, this means that data in the flow is available. A Control Flow makes it possible to enable the activation of an Action without supplying any data. This is helpful, for example, when you want to sequence two Actions with no data dependency.

The control dependency between a decision Action and a downstream Action triggered based on the result of the decision is also represented by a Control Flow. No data is communicated along the Flow other than whether or not the Control Flow activates.

In classic data flow diagrams outgoing signals are often depicted with dashed arrows suggesting that they might be control flows. In our metamodel, however, they are not since those dashed arrows don’t activate any Action internal to the Activity.