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)

Dependency Inversion

The following figure gives a zoomed-in view of the architectural elements that are relevant to our discussion of a web adapter—the adapter itself and the ports through which it interacts with our application core:

Figure 5.1: An incoming adapter talks to the application layer through dedicated incoming ports, which are interfaces implemented by the application services

The web adapter is a "driving" or "incoming" adapter. It takes requests from the outside and translates them into calls to our application core, telling it what to do. The control flow goes from the controllers in the web adapter to the services in the application layer.

The application layer provides specific ports through which the web adapter can communicate. The services implement these ports and the web adapter can call these ports.

If we look closer, we notice that this is the Dependency Inversion Principle in action. Since the control flow goes from left to...