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)

Sharing Models between Use Cases

In Chapter 4, Implementing a Use Case, I argued that different use cases should have a different input and output model, meaning that the types of input parameters and the types of return values should be different.

The following figure shows an example where two use cases share the same input model:

Figure 11.1: Sharing the input or output model between use cases leads to coupling between the use cases

The effect of sharing, in this case, is that SendMoneyUseCase and RevokeActivityUseCase are coupled to each other. If we change something within the shared SendMoneyCommand class, both use cases are affected. They share a reason to change in terms of the single responsibility principle. The same is true if both use cases share the same output model.

Sharing input and output models between use cases is valid if the use cases are functionally bound – that is, if they share a certain requirement. In this case, we actually want both use cases...