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)

An 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 already saw the Account entity in Chapter 5, Implementing a Use Case, but here is its skeleton again for reference:

Note

The Account class is not a simple data class with getters and setters but instead tries to be as immutable as possible. It only provides factory methods that create an account in a valid state, and all mutating methods do some validation, such as checking the account balance before withdrawing money, so that we cannot create an invalid domain model.

We’ll use Spring Data JPA to talk to the database, so we also need @Entity-annotated classes to represent the database state of an account:

The state of an account consists merely of an ID at this stage. Later...