Model-Based Development - Beyond Model Transformation

are refined mostly by MDA tools towards lower-level The Model Driven Architecture (MDA), as propagated by the Object Management Group, is often considered to be a milestone towards model-based development. This paper argues that MDA should merely be seen as an intermediate phase towards a truly architecture-based approach to software development. Model-based development will only succeed if we improve the communication within development projects. Architectural models must not be seen only as input of generator tools but as the primary means of knowledge transfer and as the basis of the division of labor within a project. In this context, even the object oriented paradigm might be questioned in the future. 1. Near-Term Objectives of MDA In 2000, the Object Management Group began working on Model Driven Architecture [1][2], and later announced MDA as the new strategy to develop large industrial systems. According to M. Fowler [3], “MDA is a standard approach to using the UML as a programming language”. While this statement arguably simplifies the overall direction of MDA, it surely reflects one of MDA’s major objectives, namely to provide standardized tools which allow UML diagrams to be used as input for (at least partial) code generation. As a standardization body, the OMG also intends to define a new integration level above CORBA [5], which did not really succeed to integrate middleware platforms such as J2EE [6] or .NET [7] today, the OMG consideres CORBA to be a “platform” beside J2EE and .NET [2]. In a few words, the near-term objectives of MDA can be summarized as (1) platform integration and (2) use of UML as a “programming language”. In MDA-related publications [1][2][4], “model transformation” is often presented as the basic approach to achieve these goals. The vision is that software architects or developers use a modeling language, usually UML, to create high-level (“platform independent”) models (PIM) which (“platform specific”) models (PSM) and finally executable code. 2. Long-Term Perspectives It is expected that first generation MDA tools generate only parts of the application code, i.e. manual work by application programmers is still needed. However, the declared goal of MDA proponents is to minimize or completely avoid human assistance in code generation “In a mature MDA environment, code generation will be substantial or even complete.” [1] The vision goes even further, i.e. not only code generation but also model refinement from PIM-level to PSM-level will eventually become a mostly automated and „uninteresting“ step.1 As a consequence, platforms being covered by MDA will increasingly become invisible because they will be superseded by higher-level platforms, namely MDA environments.