Resumen
Practitioners and researchers of Object Management Group Inc. (OMG) has adopted Unified Modeling Language (UML) ever since OMG's foundation in 1997. There has been a strong pressure to improve the effectiveness of UML and provide it with a multitude of new features. The original UML specifications, culminating with UML1, were based on input from a relatively large team of experts from different companies and with diverse backgrounds. It was inevitable that such diversity would result in ambiguities and semantic overlaps that have since prompted many questions about the specific meaning of certain UML concepts. A primary requirement for the future UML2 specification is their elimination by providing a precise definition of the semantics of each UML concept, including its dynamic semantics. UML2 must consolidate UML's existing features rather than add a multitude of new and changed ones. This consolidation must yield greater precision and better modularization, both crucial to achieving objectives of OMG's Model Driven Architecture.

Resumen
The article presents information on the use of Unified Modeling Language (UML) in real-time domain. All real-time systems ultimately involve interaction with the physical world. The ultimate and inevitable source of complexity in real-time software, is the physical world itself. The Unified Modeling Language [1, 2, 9] is one of the most recent examples of a modeling tool. It was designed for use with object-oriented and object-based systems and applications. In 1997, the Object Management Group, an international consortium of software vendors and users, adopted UML as a standard. Since then, interest in the UML has grown rapidly and it is becoming a lingua franca within the software community. Designing real-time software is immensely challenging not only because of timeliness constraints but also because of the need to contend with the daunting complexity of the physical world. In these circumstances, modeling is an important tool and, as has been shown in this article, UML is particularly well suited to this purpose. This is because UML incorporates most of the basic modeling abstractions that are used in the real-time domain, such as state machines and collaborations, and also because the flexibility of its stereotype mechanism allows these general abstractions to be specialized to the desired degree of accuracy. INSET: OMG'S Real-Time Analysis and Design Initiative