A Posteriori Typing for Model-Driven Engineering: Concepts, Analysis, and Applications

Model-Driven Engineering (MDE) is founded on the ability to create and process models conforming to a meta-model. In this context, classes in a meta-model are used in two ways: as templates to create objects and as (static) classifiers for them. These two aspects are inherently tied in most meta-modelling approaches, which results in unnecessarily rigid systems and hinders reusability of MDE artefacts. In this work, we discuss the benefits of decoupling object creation from typing in MDE. Thus, we rely on standard mechanisms for object creation, and propose a posteriori typing as a means to retype objects and enable multiple, partial, dynamic typings. This approach enhances flexibility; permits unanticipated reuse, as model management operations defined for a meta-model can be reused with other models once they get reclassified; and enables bidirectional model transformation by reclassification. In particular, we propose two mechanisms to realise model retyping and show their underlying theory and analysis methods. We show the feasibility of the approach by an implementation atop our meta-modelling tool METADEPTH and present several applications of retypings (transformations, reuse, and dynamicity).