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)

Implementing the domain model

We want to implement the use case of sending money from one account to another. One way to model this in an object-oriented fashion is to create an Account entity that allows us to withdraw money from a source account and deposit it into a target account:

The Account entity provides the current snapshot of an actual account. Every withdrawal from and deposit to an account is captured in an Activity entity. Since it would not be wise to always load all activities of an account into memory, the Account entity only holds a window of the last few days or weeks of activities, captured in the ActivityWindow value object.

To still be able to calculate the current account balance, the Account entity additionally has the baselineBalance attribute, representing the balance the account had just before the first activity of the activity window. The total balance, then, is the baseline balance plus the balance of all activities in the...