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


In the previous chapters, we have spent a lot of energy splitting our system into multiple, fine-grained independent components. For example, the LC application is submitted against the command-side component, whereas the status of the LC application is serviced by the query side. Because these are distinct components, there will be a time lag during which the two systems are not consistent with each other. So, querying the status of an LC application immediately after submitting may produce a stale response until the time that the query side processes the submit event and updates its internal state. In other words, the command side and the query side are considered to be eventually consistent. This is one of the trade-offs that we need to embrace when working with distributed systems.

Eric Brewer (professor emeritus of computer science at the University of California, Berkeley) formalized the trade-offs involved in building distributed systems in what is called the...