Specification of real-time properties for UML models

The Unified Modeling Language (UML) has received wide acceptance as a standard language in the field of software specification by means of different diagram types. In a recent version of UML, the textual Object Constraint Language (OCL) was introduced to support specification of constraints for UML models. But OCL currently does not provide sufficient means to specify constraints over the dynamic behavior of a model. This article presents an OCL extension that is consistent with current OCL and enables modelers to specify state-related time-bounded constraints. We consider the case study of a flexible manufacturing system and identify typical real-time constraints. The constraints are presented in our temporal OCL extension as well as in temporal logic formulae. For general application, we define a semantics of our OCL extension by means of a time-bounded temporal logic based on Computational Tree Logic (CTL).