Domain-Driven Transformation – How to Improve the Structure of Legacy Systems

Today, we know how to start a new project on a greenfield site and how to build good architecture. But most of us work in projects that have been around for a long time and whose architecture is (to put it mildly) not all that nice. “Monolith” and “Big Ball of Mud” are the unflattering terms for such systems.

In this talk, I will introduce you to Domain-Driven Transformation, a methodology, which Henning Schwentner and I have developed over the last few years from our experience of improving legacy systems. Four steps lead from the evaluation of the current state to the domain-oriented vision of the architecture. We present a catalog of refactorings that help to heal BBOM architectures, anaemic domain models and poorly organized teams. Finally, I discuss our thoughts on the influence of certain domain properties on decomposition into subdomains.