by Simon Helsen
Model-to-model transformations are a contentious topic, partly because they are not very well understood, and partly because their merit in practical model-driven development scenarios is not very clear. This is something of a ‘chicken and egg’ problem, of course, because the lack of understanding of the underlying problems and mechanisms to solve them is feeding the lack of understanding about where and how to apply these kinds of transformations.
Nevertheless, model-to-model transformations – referred to as M2M transformations – could become an important mechanism to bridge some of the abstraction gaps that occur in MSDS. Not surprisingly, countless attempts to develop M2M transformation languages have been made in academia, Open Source communities, and commercial companies.
In this chapter we focus on model-to-model transformations with the Query / View / Transformations standard of the OMG, also known as QVT. However, since the QVT standard has turned out to be a rather voluminous and complex specification, we only give a high-level overview of its architecture and features. An elaborated example is used to give you a sense of what QVT transformations look like. We also give a brief overview of its history and future, as well as a critical assessment.
A more comprehensive account is outside the scope of this book, but the adopted QVT specification document [QVT] is now publicly available from the OMG [OMG] Web site