An Extension of the UML Activity diagram to model the behaviour of Context Aware Systems

The main characteristics of context-aware systems are their ability to sense perpetually the context of the user and adapt their behavior accordingly in response to changes the user's context. Modularity is an important property for any design language as it provides ways of decomposing a system into smaller constituents which are then analyzed separately. The activity diagram of the Unified Modelling Language is a powerful language for describing the functions of a system. However it lacks notations for distinctively capture the context-awareness requirements of context-aware systems. This paper proposes an extension of the activity diagram of Unified Modelling Language with new notations that enable the separation of concerns between the system functions, the context (or environment) constraints, and the adaption actions to be performed in reaction to changes in the system's environment. The pragmatics and flexibility of the proposed extension are demonstrated using a number of real-world case studies