In fUML (Foundational UML), an execution model must be modeled as an Activity.fUML is a subset of UML that includes the ability to model behavior using UML activities, which are composed of a rich set of primitive actions1.Activities in fUML represent the executable aspects of a model and define the flow of control and data2. They are the primary means for specifying the detailed procedural logic of the behavior of a system within fUML.