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)

Example with Spring Data JPA

Let's have a look at a code example that implements AccountPersistenceAdapter from the preceding figures. This adapter will have to save and load accounts to and from the database. We saw the Account entity in Chapter 4, Implementing a Use Case, but here is its skeleton again for reference:

package buckpal.domain;

@AllArgsConstructor(access = AccessLevel.PRIVATE)

public class Account {

  @Getter private final AccountId id;

  @Getter private final ActivityWindow activityWindow;

  private final Money baselineBalance;

  public static Account withoutId(

          Money baselineBalance,

          ActivityWindow activityWindow) {

    return new Account(null, baselineBalance, activityWindow);


  public static Account withId(