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

Currently, our application resembles the diagram depicted here:

Figure 11.1 – Independent data persistence

The LC Application Processing functionality lives as its own independent component from the rest of the application. It communicates with the monolith through the exchange of domain events using the event bus. It makes use of its own persistence store and exposes HTTP-based APIs that the frontend consumes. Let’s examine whether it is possible to further decompose the application into finer-grained components. The AutoApprovalSaga component currently lives within the confines of the monolith, but this is mostly an artifact of our previous design as opposed to an intentional design choice. Let’s look at how we can extract this into its own component next.

Saga as a standalone component

Currently, the AutoApprovalSaga component (discussed in detail in Chapter 8, Implementing Long-Running Workflows...