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)

The "One-Way" Mapping Strategy

There is yet another mapping strategy with another set of pros and cons – the "one-way" strategy sketched in the following figure:

Figure 8.4: With the domain model and the adapter models implementing the same "state" interface, each layer only needs to map objects it receives from other layers – one way

In this strategy, the models in all layers implement the same interface, which encapsulates the state of the domain model by providing getter methods for the relevant attributes.

The domain model itself can implement a rich behavior, which we can access from our services within the application layer. If we want to pass a domain object to the outer layers, we can do so without mapping, since the domain object implements the state interface expected by the incoming and outgoing ports.

The outer layers can then decide whether they can work with the interface or whether they need to map it into their own model...