xUML epitomizes the convergence of visual modeling with model manipulation programming. The results of this merger are executable models and model-driven software development. This chapter presents the fundamental notions of constructing executable domain models with xUML, as well as the principles of the MDA approach. In particular, we define the new roles of the developers in development processes based on MDA and the MDA activity workflow. We discuss also the output artifacts from each activity. As new technologies require new software development processes, we present an iterative and incremental model-driven process, combined with techniques for project planning and progress estimation based on BERT and ERNIE. We show how model executability creates congenial conditions for the application of higher-order cognitive skills in the software development process, and for the substitution of liberal creativity with design automation.