Preface

Domain-driven design (DDD) makes available a set of principles, patterns, and techniques that subject-matter experts, architects, developers, and other team members can adopt to work together and decompose complex systems into well-factored, collaborative, and loosely coupled subsystems. When Eric Evans introduced these concepts in the early 2000s, in a lot of ways, these principles were way ahead of their time. We were firmly in the age of the monolith, service-oriented architectures (SOAs) as a concept were just starting to take root, and the cloud, microservices, continuous delivery, and so on didn’t even exist yet! While it was relatively easy to adopt some of its tactical aspects, the strategic side of DDD was still seen as an unjustifiable overhead for the most part.

Fast-forwarding to today, we are building our most complex software solutions ever, with even more complex organization and team structures to cope. Also, the use of the public cloud is almost a given. This has given rise to a situation where distributed teams and applications are almost a norm. Also, we are also in an age where applications from an earlier generation need to be modernized. All this has resulted in the principles of DDD, specifically the strategic elements, gaining a lot of prominence.

We have been practitioners of these concepts and have gained valuable insights from our experiences. Over the years, we have seen a number of advancements that have made the adoption of DDD at scale a viable option. This book is a distillation of all our collective experiences. While we have drawn a lot of inspiration from earlier works on the subject, we have been very conscious to apply a practitioner’s mindset so that we lower the barrier for teams looking to sustain and thrive in their journey of building complex, distributed software.