Five years on from its adoption in 1997 by the Object Management Group
(OMG), the Uni?ed Modeling Language is the de facto standard for
creating - agrammatic models of software systems. More than 100 books
have been written about UML, and it is taught to students throughout the
world. The de?nition of UML version 2 is well under way, and should be
largely completed within the year. This will not only improve and
enhance UML itself, including standard facilities for diagram
interchange, but also make it fully integrated with other modeling
technologies from the OMG, such as Meta-Object Facility (MOF) and XML
Metadata Interchange (XMI). The Object Constraint Language, which has
become an important vehicle for communicating detailed insights between
UML researchers and practitioners, will have a much expanded
speci?cation and be better integrated with the UML. The popularity of
UML signi?es the possibility of a shift of immense prop- tions in the
practice of software development, at least comparable to the shift from
the use of assembly language to "third-generation" or "high-level" p-
gramming languages. We dream of describing the behavior of software
systems in terms of models, closely related to the needs of the
enterprise being served, and being able to routinely translate these
models automatically into executing p- grams on distributed computing
systems. The OMG is promoting Model-Driven Architecture (MDA) as a
signi?cant step towards this vision, and the MDA c- cept has received
considerable support within the IT industry.