Book Image

Get Your Hands Dirty on Clean Architecture - Second Edition

By : Tom Hombergs
4 (1)
Book Image

Get Your Hands Dirty on Clean Architecture - Second Edition

4 (1)
By: Tom Hombergs

Overview of this book

Building for maintainability is key to keep development costs low (and developers happy). 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. Building upon the success of the first edition, this comprehensive guide explores the drawbacks of conventional layered architecture and highlights the advantages of domain-centric styles such as Robert C. Martin's Clean Architecture and Alistair Cockburn's Hexagonal Architecture. Then, the book dives into hands-on chapters that show you how to manifest a Hexagonal Architecture in actual code. You'll learn in detail about different mapping strategies between the layers of a Hexagonal Architecture and see how to assemble the architecture elements into an application. The later chapters demonstrate how to enforce architecture boundaries, what 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. Whether you're a seasoned developer or a newcomer to the field, "Get Your Hands Dirty on Clean Architecture" will empower you to take your software architecture skills to new heights and build applications that stand the test of time.
Table of Contents (18 chapters)

A use case in a nutshell

First, let’s discuss what a use case actually does. Usually, it follows these steps:

  1. Take the input.
  2. Validate the business rules.
  3. Manipulate the model state.
  4. Return the output.

A use case takes input from an incoming adapter. You might wonder why I didn’t call the first step Validate input. The answer is that I believe use case code should only be concerned with domain logic and we shouldn’t pollute it with input validation. So, we’ll do input validation somewhere else, as we’ll see shortly.

The use case is, however, responsible for validating business rules. It shares this responsibility with the domain entities. We’ll discuss the distinction between input validation and business rule validation later in this chapter.

If the business rules were satisfied, the use case then manipulates the state of the model in one way or another, based on the input. Usually, it will change the state...