Domain-Driven Transformation: How to return structure to legacy systems

Today, we know how to start a new greenfield project with a good architecture. However, most of us work on systems that have been under development for a long time and whose architecture is not quite so nice (to put it mildly). "Monolith" and "Big Ball of Mud" are the unflattering terms for such systems, and in this keynote I will introduce you to Domain-Driven Transformation. A methodology that Henning Schwentner and I have developed in recent years from our experience of improving legacy systems. Four steps lead from the evaluation of the current state to the domain-orientated vision of the architecture. We present a catalogue of refactorings that help to heal BBOM architectures, anaemic domain models and poorly organised teams. Finally, I discuss our thoughts on the influence of certain domain properties on decomposition into subdomains.