Software development is inherently difficult because of the complexity of the task and the high level of change that occurs during its lifecycle. Attempts to solve these problems have raised the level of abstraction dramatically. Nevertheless, recent propositions have generated much skepticism. Approaches such as visual languages or CASE tools have not fundamentally changed the state of the practice in software development, mostly due to the cost involved in producing the code generation modules. In this book, this problem is analyzed and a new extension mechanism for UML is presented. More...