A query structured approach to model transformation

Model Transformation (MT) is an important operation in the domain of Model-Driven Engineering (MDE). While MDE continues to be further adopted in the design and development of systems, MT programs are applied to more and more complex configurations of models and relationships between them and grow in complexity. Structured techniques have proven to be helpful in design and development of programming languages. In this paper, using an example, we explain an approach in which MT specifications are defined in a structured manner, by distinguishing queries as their main building blocks. We call the approach Query Structured Transformation (QueST). We demonstrate that the contents of individual queries used in QueST to define a transformation are dispersed all over the entire corresponding MT definition in ETL or QVT-R. Our claim is that the latter two languages are less supportive of a structured approach than QueST. Finally we discuss the promising advantage of QueST in MT definition, and possible obstacles towards using it.