Modeling time in object-oriented specifications of real-time imaging systems

Real-time imaging systems are expected to perform at a rate set by the operating environment. This places additional temporal constraints on the implementation, and has led to advance in parallel processing and optimization. The constraints are also applied. however. to the analysis and design models of the system,, an aspect that has received far less consideration. particularly outside of academia. It is well understood that the earlier a bug is discovered the cheaper the fix and this is taken to the extent that,, if an error can be found during design or even analysis. the repair can be several orders of magnitude cheaper. It is therefore an economic imperative that the analysis and design models are sufficiently expressive such that the flaws in the models can be discovered before they are implemented, and this applies equally to real-time constraints. To achieve this a change in the modeling languages used is needed. An approach that offers potential in this respect is proposed here. The Unified Modeling Language is used as the basis for a transformation of the design model into a formal description of the system which is amenable to simulation and rigorous proving. The application of the UML in building a system model is presented informally and illustrated by means of a simple example.