Modeling Control Flow with Activity Diagrams

The Unified Modeling Language (UML) 1 is a visual, object-oriented, and multipurpose modeling language. While primarily designed for modeling software systems, it can also be used for business process modeling. Since the early 70s, a large variety of languages for data and software modeling like entity-relationship diagrams [2], message sequence charts [5, 10], state-charts [9], etc. have been developed, each of them focusing on a different aspect of software structure or behavior. In the early 90s, object-oriented design approaches gained increasing attention, for instance, in the work of The UML emerged from the intention of Rumbaugh, Booch, and Jacobson to find a common framework for their approaches and notations. Furthermore, the language was also influenced by other object-oriented approaches like, e.g., Coad/Yourdon [3]. The first version UML 1.0 [20] was released in 1997 and accepted as a standard by the Object Management Group (OMG) 2 the same year. The OMG, taking over the responsibility for the evolution of the UML from then on, is a consortium from both industry and academia also responsible for other well-known initiatives like CORBA, MDA, and XMI. OMG specifications have to undergo a sophisticated adoption process before being agreed upon as a standard by the OMG members. Since many important tool builders and influential software companies are involved in the OMG, UML has quickly been accepted by the software industry, especially since