Book Image

Domain-Driven Design with Java - A Practitioner's Guide

By : Premanand Chandrasekaran, Karthik Krishnan
Book Image

Domain-Driven Design with Java - A Practitioner's Guide

By: Premanand Chandrasekaran, Karthik Krishnan

Overview of this book

Domain-Driven Design (DDD) makes available a set of techniques and patterns that enable domain experts, architects, and developers to work together to decompose complex business problems into a set of well-factored, collaborating, and loosely coupled subsystems. This practical guide will help you as a developer and architect to put your knowledge to work in order to create elegant software designs that are enjoyable to work with and easy to reason about. You'll begin with an introduction to the concepts of domain-driven design and discover various ways to apply them in real-world scenarios. You'll also appreciate how DDD is extremely relevant when creating cloud native solutions that employ modern techniques such as event-driven microservices and fine-grained architectures. As you advance through the chapters, you'll get acquainted with core DDD’s strategic design concepts such as the ubiquitous language, context maps, bounded contexts, and tactical design elements like aggregates and domain models and events. You'll understand how to apply modern, lightweight modeling techniques such as business value canvas, Wardley mapping, domain storytelling, and event storming, while also learning how to test-drive the system to create solutions that exhibit high degrees of internal quality. By the end of this software design book, you'll be able to architect, design, and implement robust, resilient, and performant distributed software solutions.
Table of Contents (17 chapters)
Part 1: Foundations
Part 2: Real-World DDD
Part 3: Evolution Patterns

Continuing our design journey

In the previous chapter, we discussed eventstorming as a lightweight method to clarify business flows. As a reminder, this is the output produced from our eventstorming session:

Figure 5.1 – Recap of the eventstorming session

As mentioned previously, the blue stickies in this diagram represent commands. We will be using the Command Query Responsibility Segregation (CQRS) pattern as a high-level architecture approach to implement the domain logic for our LC issuance application. Let’s examine the mechanics of using CQRS and how it can result in an elegant solution. For a recap of what CQRS is and when it is appropriate to apply this pattern, please refer to the When to use CQRS section in Chapter 2, Where and How Does DDD Fit?.

Important Note

CQRS is by no means a silver bullet. Although it is general-purpose enough to be used in a variety of scenarios, it is a paradigm shift as applied to mainstream software...