Four Discourses on Domain-Driven Design: Bridging the Practical and Academic Schools

This article presents the author's systematic analysis of Domain-Driven Design (DDD) methodology, organized into four fundamental discourses: Structure (tactical and strategic modeling), Process (refactoring and software engineering), Language (model-based unified language), and Modeling (model-driven domain modeling).

The author draws inspiration from Feng Youlan's philosophical approach of "teaching what has been said" versus "innovating on what was said" to categorize DDD literature into two schools: the practical "folk school" emphasizing personal insight and ideological systems, and the academic "school" emphasizing standards and systematic training. The article aims to bridge these two approaches.

Key topics include: the nature of software complexity as discussed in Brooks' "No Silver Bullet" (1986); strategic design principles including Context Mapping, Refinement, and Large-Scale Structure; tactical design covering building blocks (entities, value objects, services, repositories, aggregates, factories) and flexible design principles; the role of refactoring in deepening understanding; agile development and continuous delivery practices; and the concept of Ubiquitous Language for team communication.

The article also explores the relationship between DDD and other modeling approaches (UML/SysML), proposing that Bounded Context can be understood as equivalent to UML classes or SysML blocks. The author suggests that DDD, while valuable, has not introduced fundamentally new concepts but rather reconceptualized existing software engineering knowledge through different terminology.