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)

Slicing Persistence Adapters

In the preceding figures, we have seen a single persistence adapter class that implements all persistence ports. There is no rule, however, that forbids us to create more than one class, as long as all persistence ports are implemented.

We might choose, for instance, to implement one persistence adapter per domain class for which we need persistence operations (or "aggregate" in DDD lingo), as shown in the following figure:

Figure 6.4: We can create multiple persistence adapters, one for each aggregate

This way, our persistence adapters are automatically sliced along the seams of the domain that we support with persistence functionality.

We might split our persistence adapters into even more classes, for instance, when we want to implement a couple of persistence ports using JPA or another OR-Mapper and some other ports using plain SQL for better performance. We might then create one JPA adapter and one plain SQL adapter, each implementing...