SimStudio is a Modeling & Simulation framework based on the DEVS formalism (Discrete EVent Systems Specification). SimStudio architecture aims at integrating in a single platform tools for modeling, simulation, analysis and collaboration, by proposing model transformation features (code generation, among others) in order to smooth the modeling and simulation cycle. To achieve this, SimStudio is built upon the DEVS formalism, recognize by many as a "universal" simulation formalism, and upon a unifying language for representing DEVS models. Models are at the heart of the infrastructure we propose, in line with the Model-Driven Engineering (MDE) approach, at the boundary between software engineering and simulation.