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)

Using Domain Entities as Input or Output Models

If we have an Account domain entity and an incoming port, SendMoneyUseCase, we might be tempted to use the entity as the input and/or output model of the incoming port, as shown in the following figure:

Figure 11.2: Using a domain entity as the input or output model of a use case couples the domain entity to the use case

The incoming port has a dependency on the domain entity. The consequence of this is that we have added another reason for the Account entity to change.

Wait, the Account entity doesn't have a dependency on the SendMoneyUseCase incoming port (it's the other way around), so how can the incoming port be a reason to change for the entity?

Say we need some information about an account in the use case that is not currently available in the Account entity. This information is ultimately not to be stored in the Account entity, however, but in a different domain or bounded context. We are tempted to add a new field...