Abstract. Language-centric methodologies, triggered by the success of Domain Specific Languages, rely on precise specifications of modeling languages. While the definition of the abstract syntax is standardized by the 4-layer metamodel architecture of the OMG, most language specifications are held informally for the description of the semantics and the (graphical) concrete syntax. This paper is tackling the problem of specifying the concrete syntax of a language in a formal and non-ambiguous way. We propose to define the concrete syntax by an extension of the already existing metamodel of the abstract syntax, which describes the concepts of the language, with a second layer describing the graphical representation of concepts by visual elements. In addition, an intermediate layer defines how elements of both layers are related to each other. Unlike similar approaches that became the basis of some CASE tools, the intermediate layer is not a pure mapping from abstract to concrete syntax but connects both layers in a flexible, declarative way. We illustrate our approach with a simplified form of statecharts.

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Abstract. Model-driven engineering and model-based approaches have permeated all branches of software engineering to the point that it seems that we are using models, as Molière's Monsieur Jourdain was using prose, without knowing it. At the heart of modeling, there is a relation that we establish to represent something by something else. In this paper we review various definitions of models and relations between them. Then, we define a canonical set of relations that can be used to express various kinds of representation relations and we propose a graphical concrete syntax to represent these relations. We also define a structural definition for this language in the form of a metamodel and a formal interpretation using Prolog. Hence, this paper is a contribution towards a theory of modeling.

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The era of distributed systems is upon us. Middlewarespecific concerns, and especially the distribution concern, which is the core of any middleware-mediated application, are addressed every day in all sorts of enterprise systems. However, object-oriented UML designs offer a very limited perspective on what exactly is distributed, how exactly the distribution is achieved, and where exactly distributed services are located. In order to answer these questions, the MDA-compliant Enterprise Fondue method proposes a hierarchy of UML profiles as a means for addressing the distribution concern at three different MDA-levels of abstraction. Model transformations are provided to incrementally refine existing design models according to the proposed profiles. For the last phase of the Enterprise Fondue process, code generation for specific middleware infrastructures is supported through the Parallax framework. The CORBA technology is used for illustrating the entire approach on a concrete example.