Component-Based Real-Time Design: Mapping HRT-HOOD to UML

HRT-HOOD has methodological strengths that deserve to be preserved in the face of the commercial decline of HOOD technology. The UML (Unified Modeling Language) meta-model, on the other hand, has a level of flexibility that makes it an especially attractive platform to express the specific real-time design minded features of the HRT-HOOD method. The object-oriented connotation of the method that results from mapping HRT-HOOD onto UML raises methodological issues that we deem of interest to the real-time community at large. This paper discusses three such issues in particular: the prevalence of objects over classes in real-time design, with the consequent inversion of the standard object-oriented development paradigm; the need to derive classes "by example", which arises from the demand to allow multiple, yet static, instances of real-time objects initially designed as singleton; the opportunity of reuse-oriented component-based real-time development, which descends from using interfaces instead of classes as the target of associations among objects.