Chapter 1: The Rationale for Domain-Driven Design

The being cannot be termed rational or virtuous, who obeys any authority, but that of reason.

— Mary Wollstonecraft

According to the Project Management Institute’s (PMI’s) Pulse of the Profession report published in February 2020, only 77% of all projects meet their intended goals—and even this is true only in the most mature organizations. For less mature organizations, this number falls to just 56%; that is, approximately one in every two projects does not meet its intended goals. Furthermore, approximately one in every five projects is declared an outright failure. At the same time, we also seem to be embarking on our most ambitious and complex projects.

In this chapter, we will examine the main causes of project failure and look at how applying domain-driven design (DDD) provides a set of guidelines and techniques to improve the odds of success in our favor. While Eric Evans wrote his classic book on the subject way back in 2003, we look at why that work is still extremely relevant in today’s times.

In this chapter, we will cover the following topics:

• Understanding why software projects fail
• Characteristics of modern systems and dealing with complexity
• Introduction to DDD
• Reviewing why DDD is relevant today

By the end of this chapter, you will have gained a basic understanding of DDD and why you should strongly consider applying the tenets of DDD when architecting/implementing modern software applications, especially the more complex ones.