Engineering Intelligent Systems

8A Time for Timeboxes and the Use of Usage Processes

Time is an illusion

(Albert Einstein)

Despite Einstein's assertion, we seem to live in time. We imagine life to be the passage of time, and time is essential for nearly all our activities. Time is also essential to our systems and their design. To use a system is to use it in time. No use case takes place outside of time or in zero time. Time is also important inside of a use case. Response time of a system to a human user's button press or screen tap can make the difference between usability and a failed product.

To design intelligent systems, we need better ways of describing how a system works in time, what happens when, in what sequence, and what behavior can happen concurrently. Despite the fact that nothing could be more intuitive than dealing with the past, present, and future of time, behavioral system models can cause unnecessary confusion due to an inattention to the representation of time. Analyzing how human beings think about and relate to time in everyday life sheds new light on how the complex behavior of systems can be represented. For instance, the past is easily represented on a timeline, because past events are seen – in hindsight – as occurring linearly. Processes represented as flow charts or activity diagrams usually appear to be happening in the present, as if all actions were taking place in the infinitesimally short period of time we know as the present moment. The future, in contrast, is seen as ...