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)

Implementing a Persistence Adapter

In Chapter 1, What's Wrong with Layers?, I ranted about the traditional layered architecture and claimed that it supports "database-driven design" because, in the end, everything depends on the persistence layer. In this chapter, we will have a look at how to make the persistence layer a plugin to the application layer to invert this dependency.

Dependency Inversion

Instead of a persistence layer, we will talk about a persistence adapter that provides persistence functionality to the application services.

The following figure shows how we can apply the Dependency Inversion Principle to do just that:

Figure 6.1: The services from the core use ports to access the persistence adapter

Our application services call port interfaces to access persistence functionality. These ports are implemented by a persistence adapter class that does the actual persistence work and is responsible for talking to the database...