Overcoming The Limitations of Signal Handling when Simulating UML 2 Activity Charts

Our approach to Model Driven Development uses UML 2 activity charts for simulating and implementing the control flow of an application. Signal handling is an important concept of these diagrams for synchronizing actions. We identified multiple problems related to buffering and distributing signals as well as to specifying targets for UML SendSignalActions and BroadcastSignalActions. We propose solutions for these issues by defining UML tags to configure activities and nodes and by introducing SignalPath, a subset of the XPath language, for querying the object graph at runtime to obtain targets for send actions. Our approach has successfully been implemented in our simulation environment for UML 2 activity charts.