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)

What about Database Transactions?

We have not touched upon the topic of database transactions yet. Where do we put our transaction boundaries?

A transaction should span all write operations to the database that are performed within a certain use case so that all those operations can be rolled back together if one of them fails.

Since the persistence adapter doesn't know which other database operations are part of the same use case, it cannot decide when to open and close a transaction. We have to delegate this responsibility to the services that orchestrate the calls to the persistence adapter.

The easiest way to do this with Java and Spring is to add the @Transactional annotation to the application service classes so that Spring will wrap all public methods with a transaction:

package buckpal.application.service;


public class SendMoneyService implements SendMoneyUseCase {



If we want our services to stay pure and not be stained with @Transactional annotations...