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

Changes in database interactions

While we have extracted our application component into its own unit, we continue to be coupled at the database tier. If we are to achieve true independence from the monolith, we need to break this database dependency. Let’s look at the changes involved in making this happen.

Data migration

As a first step to start using a database of our own, we will need to start migrating data from the command side event store and the query store(s), as shown here:

Figure 10.10 – Data migration

In our case, we have the command side event store and the query store(s) that will need to be migrated out. To minimize effort from the outset, it might be prudent to do a simple homogenous migration by keeping the source and target database technologies identical. In advance of the cut-over, among other things, it will be essential to do the following:

  • Profile to make sure that latency numbers are within tolerable limits...