Book Image

Get Your Hands Dirty on Clean Architecture

By : Tom Hombergs
Book Image

Get Your Hands Dirty on Clean Architecture

By: Tom Hombergs

Overview of this book

Building for maintainability is key to keeping development costs low and processes easy. The second edition of Get Your Hands Dirty on Clean Architecture is here to equip you with the essential skills and knowledge to build maintainable software. With this comprehensive guide, you’ll explore the drawbacks of conventional layered architecture and the advantages of domain-centric styles such as Robert C. Martin's Clean Architecture and Alistair Cockburn's Hexagonal Architecture. Then, you’ll dive into hands-on explanations on how to convert hexagonal architecture into actual code. You'll learn in detail about different mapping strategies between the layers of hexagonal architecture and discover how to assemble the architectural elements into an application. Additionally, you’ll understand how to enforce architecture boundaries, which shortcuts produce what types of technical debt, and how, sometimes, it is a good idea to willingly take on those debts. By the end of this second edition, you'll be armed with a deep understanding of the hexagonal architecture style and be ready to create maintainable web applications that save money and time.
Table of Contents (13 chapters)

Organizing by Layer

The first approach to organizing our code is by layer. We might organize a code like this:

Figure 3.1: When organizing code by layer, functional aspects tend to be mixed

For each of our layers, web, domain, and persistence, we have a dedicated package. As discussed in Chapter 1, What's Wrong with Layers?, simple layers may not be the best structure for our code for several reasons, so we have already applied the Dependency Inversion Principle here, only allowing dependencies toward the domain code in the domain package. We did this by introducing the AccountRepository interface in the domain package and implementing it in the persistence package.

However, we can find at least three reasons why this package structure is suboptimal.

First, we have no package boundary between functional slices or features of our application. If we add a feature for managing users, we will add a UserController to the web package, a UserService, UserRepository, and User to...