You're reading from Designing Hexagonal Architecture with Java An architect's guide to building maintainable and change-tolerant applications with Java and Quarkus

Product type Paperback

Published in Jan 2022

Publisher Packt

ISBN-13 9781801816489

Length 460 pages

Edition 1st Edition

Languages

Java

Tools

Quarkus

Concepts

Software Architecture

Author (1):

Davi Vieira

View More author details

Table of Contents (21) Chapters

Preface

1. Section 1: Architecture Fundamentals

2. Chapter 1: Why Hexagonal Architecture? FREE CHAPTER

3. Chapter 2: Wrapping Business Rules inside Domain Hexagon

4. Chapter 3: Handling Behavior with Ports and Use Cases

5. Chapter 4: Creating Adapters to Interact with the Outside World

6. Chapter 5: Exploring the Nature of Driving and Driven Operations

7. Section 2: Using Hexagons to Create a Solid Foundation

8. Chapter 6: Building the Domain Hexagon

9. Chapter 7: Building the Application Hexagon

10. Chapter 8: Building the Framework Hexagon

11. Chapter 9: Applying Dependency Inversion with Java Modules

12. Section 3: Becoming Cloud-Native

13. Chapter 10: Adding Quarkus to a Modularized Hexagonal Application

14. Chapter 11: Leveraging CDI Beans to Manage Ports and Use Cases

15. Chapter 12: Using RESTEasy Reactive to Implement Input Adapters

16. Chapter 13: Persisting Data with Output Adapters and Hibernate Reactive

17. Chapter 14: Setting Up Dockerfile and Kubernetes Objects for Cloud Deployment

18. Chapter 15: Good Design Practices for Your Hexagonal Application

19. Assessments

20. Other Books You May Enjoy

Chapter 2: Wrapping Business Rules inside Domain Hexagon

In the previous chapter, we learned about the Domain as the first hexagon in hexagonal architecture. By being the innermost hexagon, the Domain does not depend on anything above it. Also, we make all the other hexagons depend on the Domain to conduct their operations. This kind of arrangement confers the Domain hexagon a degree of responsibility and relevance far higher than other hexagons. We employ such an arrangement because it is on a domain where we group all the business rules and data that most represent the problem we are trying to solve.

Among the techniques to model a problem domain, Domain Driven Design (DDD) is widely adopted in projects that emphasize software code as a medium to convey knowledge about a business. An always-present concern to separate what constitutes the core problem domain and what is secondary to it makes DDD a suitable approach to support the hexagonal architecture goal to separate technology...