Sidebar: Waiting for UML 2.0

Computerworld - When IBM acquired Rational Software Corp., the company gained the expertise of two technologists who have been instrumental in the development of the Unified Modeling Language (UML).
Grady Booch, Rational's former chief technology officer who is now an IBM fellow, is considered a father of UML, since the standard is based on the modeling language he created. Bran Selic, a distinguished engineer in IBM's Rational Software division, co-chairs a task force that is finalizing the new UML 2.0 standard with the Object Management Group.
Booch and Selic recently spoke with Computerworld about UML 2.0, which is expected to be finalized by midyear.
What are the major differences between UML 1.5 and the upcoming 2.0 version?
Selic: In 1.5, we introduced something called the action semantics, which is a way of modeling some of the fine-grain detail that comes in with specifying models, maybe even down to the level of individual instructions. Along with that came this idea of describing what that actually means in terms of the runtime. How is this thing executed? What does a program that this thing models look like? And that introduced something which was a key element of the UML 2.0 -- a very precise definition of the semantics or the meaning of these models in the sense that one could now, for example, take a UML model and directly translate it, in some cases, into programs directly. This is part of a much more general thing called Model Driven Architecture (MDA), which is shifting the focus from the programs toward models, because models are much closer to the way that people writing applications or at least using applications think about their problems. It's a higher level of abstraction.
One of the fundamental inputs to UML 2.0 was support for Model Driven Architecture and model-driven development [MDD]. That required a somewhat greater precision of UML than there was originally in the spec. ... The other one that I would single out as being a major influence is the ability to model very large heterogeneous systems so that one could describe the architectures of these systems quite succinctly.
The project in formulating UML 2.0 started almost three years ago, and we are now in the closing stages of adopting the standard. We have released one version so that people who are building tools that conform to the standard can look at it and come back with feedback. And various researchers and other people who are interested in UML and model-driven development are looking at the spec