Bosco is a code generation tool, which goal is to accept any MOF model as parameter and follow the evolution of OMG standards. It generates the underlying model (also called repository) for any modeling language expressed in MOF. In other words, it reads XMI files and generates the corresponding source code, in different object-oriented languages (Java, Eiffel, Python, C++). In the case of Java, the generated code implements the JMI specification. In Bosco, any user can program add-ins at each level using the visitor pattern and the template technology.