Consistent co-evolution of models and transformations

Evolving metamodels are in the center of Model-Driven Engineering, necessitating the co-evolution of dependent artifacts like models and transformations. While model co-evolution has been extensively studied, transformation co-evolution has received less attention up to now. Current approaches for transformation co-evolution provide a fixed, restricted set of metamodel (MM) changes, only. Furthermore, composite changes are treated as monolithic units, which may lead to inconsistent co-evolution for overlapping atomic changes and prohibits extensibility. Finally, transformation co-evolution is considered in isolation, possibly inducing inconsistencies between model and transformation co-evolution. To overcome these limitations, we propose a complete set of atomic MM changes being able to describe arbitrary MM evolutions. Reusability and extensibility are supported by means of change composition, ensuring an intra-artifact consistent co-evolution. Furthermore, each change provides resolution actions for both, models and transformations, ensuring an inter-artifact consistent co-evolution. Based on our conceptual approach, a prototypical implementation is presented.