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

Implementation patterns

We have looked at integration between bounded contexts at a design level, but these concepts need to be translated into code. There are three broad categories that can be employed when integrating two bounded contexts:

  • Data-based
  • Code-based
  • API-based

Let’s look at each method in more detail now.


In this style of integration, the bounded contexts in question share data with each other. If the relationship is symmetric, the teams owning these bounded contexts may choose to share entire databases with free access to read, write, and change underlying structures. Conversely, in an asymmetric relationship, the supplier may constrain the scope of access, based on the type of relationship.

Shared database

The simplest form of data integration is the use of a shared database. In this style of integration, all participating bounded contexts have unrestricted access to the schemas and the underlying data, as shown here...