Abstract. Technological and business changes influence the evolution of software systems. When this happens, the software artifacts may need to be adapted to the changes. This need is rapidly increasing in systems built using the Model-Driven Engineering (MDE) paradigm. An MDE system basically consists of metamodels, terminal models, and transformations. The evolution of a metamodel may render its related terminal models and transformations invalid. This paper proposes a three-step solution that automatically adapts terminal models to their evolving metamodels. The first step computes the equivalences and (simple and complex) changes between a given metamodel, and a former version of the same metamodel. The second step translates the equivalences and differences into an adaptation transformation. This transformation can then be executed in a third step to adapt to the new version any terminal model conforming to the former version. We validate our ideas by implementing a prototype based on the AtlanMod Model Management Architecture (AMMA) platform. We present the accuracy and performance that the prototype delivers on two concrete examples: a Petri Net metamodel from the research literature, and the Netbeans Java metamodel.

This paper shows how an attempt at a uniform and reflective definition resulted in an open-ended system supporting ObjVlisp, which we use to simulate object-oriented language extensions.We propose to unify Smalltalk classes and their terminal instances. This unification allows us to treat a class as a "first class citizen", to give a circular definition of the first metaclass, to access to the metaclass level and finally to control the instantiation link. Because each object is an instance of another one and because a metaclass is a real class inheriting from another one, the metaclass links can be created indefinitely.This uniformity allows us to define the class variables at the metalevel thus suppressing the Smalltalkambiguity between class variables and instance variables: in our model the instance variables of a class are the class variables of its instances.

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Reflective programming languages are those where users' programs are allowed to customize in an organized way the behavior of the language to their own needs. For ten years now, most of the work on reflection revolved around the definition and the implementation of metaobject protocols which express this organization. No methodologies have been proposed for reflective programming per se . This paper proposes a first one aiming at the design of composable metaobjects. Given two independently developed reflective customizations, this methodology proposes principles to be observed in their design such that they can be composed using standard base-level aggregation or specialization. While this paper focuses on a simple MOP and illustrates the methodology on specific examples, this methodology can be generalized to other languages with different MOPs. For instance, we discuss how to adapt it to C LOS .