Aspect-oriented metamodelling.

The Object Management Group's (OMG) Model Driven Architecture (MDA)
strategy envisages a world where models play a more direct role in software pro-
duction. To ensure that the burden of maintaining more than one formal model
does not outweigh the potential bene�ts, powerful tool support is required. How-
ever, each domain, organisation, even project, is likely to need its own particular
process supported by its own particular con�guration of modelling languages. The
challenge is to provide de�nitions of languages that not only support the con�g-
uration and extension of those languages for use with particular processes, but
also can be used directly in the customisation/generation of tools. This paper de-
scribes an aspect-oriented, metamodelling approach to language de�nition which
aims to meet this challenge. This exploits two mechanisms (package extension
and package templates), which are similar to mechanisms proposed to support
aspect-oriented design with UML. Thus the paper can also be viewed as describ-
ing a case study in aspect oriented design. The approach is illustrated by extracts
from the 2U submission to the UML 2.0 RFPs issued by the OMG in 2001. The
paper concludes with a discussion on the customisation and generation of tools
from such de�nitions.