The benefits of model-based development come from the interaction of pro- cess and product models and their realization in a CASE tool: Firstly, complex design steps such as refactorings or the introduction of complex communication patterns between components can be naturally defined and performed in a tool. Secondly, the application of such design steps naturally leads to a development history that can be recorded in the tool and used for a kind of high-level configuration and version management. Finally, the requirements and design rationales that influence design steps can be traced and documented throughout the complete development process.