An Interactive Viewpoint on the Role of UML

The role of the Unified Modeling Language (UML) is to model interactive systems, whose behaviors emerge from the interaction of their components with each other and with the environment. Unlike traditional (algorithmic) computation, interactive computation involves infinite and dynamic (late binding) input/output streams. Algorithmic tools and models do not suffice to express the behavior of today’s interactive systems, which are capable of self-reconfiguring and adapting to their environment. Whereas procedural languages may express precise designs of closed processes, UML provides support for the inherently open-ended preliminary steps of system analysis and specification, which are becoming increasingly complex. Interactive systems require dynamic models where interaction has first-class status, and where the environment is modeled explicitly, as actors whose roles constrain the input patterns. UML’s interaction-based approach to system modeling fits well with the encapsulation-based OO approach to implementation. By coupling these approaches, the software engineering process can provide a complete solution to system design and implementation. A theoretical framework for modeling interactive computing can strengthen the foundations of UML and guide its evolution.