Structured Nodes in UML 2.0 Activities

The upcoming major revision of the UML (see OMG [2003]) has introduced significant changes and additions to “the lingua franca of Software Engineering”. Within the UML, activity diagrams are particularly prominent, since they are the natural choice when it comes to the modeling of web-services, workflows, and service-oriented architectures. One of the most novel concepts introduced are so called structured nodes (StructuredActivityNodes in the metamodel). This concept includes features like loops, expansion regions, collection valued parameters, and data streaming. Building on substantial previous work by the author, the purpose of this paper is to understand better these new concepts and notations, and actually defines a semantics for them. Since the UML standard is still immature in some parts, this article is restricted to those concepts, for which a reliable interpretation is currently possible. This article is followup to Störrle [2004d]. ACM CCS