Designing Hexagonal Architecture with Java: The definitive guide to building maintainable and long-lasting applications with java and quarkus, 2nd Edition

Learn how to build robust, change-tolerable, and highly maintainable cloud-native Java applications with Hexagonal Architecture and Quarkus.

Key Features

• Use hexagonal architecture to increase maintainability and reduce technical debt
• Learn how to build systems that are simple to change and understand
• Leverage Quarkus to create modern cloud-native applications

Book Description

We live in a fast-evolving world with new technologies emerging every day, where enterprises are constantly changing in an unending quest to be more profitable. So how to develop software capable of handling such a high level of unpredictability? With this question in mind, this book explores how hexagonal architecture can help build robust, change-tolerable, maintainable, and cloud-native applications that can meet the needs of enterprises seeking to increase their profits while dealing with uncertainties. This book starts covering hexagonal architecture's building blocks, such as entities, use cases, ports, and adapters. You'll learn to assemble business code in the Domain hexagon, create features with ports and use cases in the Application hexagon, and make your software compatible with different technologies by employing adapters in the Framework hexagon. In this new edition, you will learn the differences between hexagonal and layered architecture and how to apply SOLID principles while developing a hexagonal system based on a real-world scenario. Finally, you'll get to grips with using Quarkus to turn your hexagonal application into a cloud-native system. By the end of this book, you'll be able to develop robust, flexible, and maintainable systems that will stand the test of time.

What you will learn

• Learn how to apply SOLID principles with hexagonal architecture
• Find out how to assemble business rules algorithms using the specification design pattern
• Combine domain-driven design techniques with hexagonal principles to create powerful domain models
• Employ adapters to make the system support different protocols such as REST, gRPC, and WebSocket
• Create a module and package structure based on hexagonal principles
• Use Java modules to enforce dependency inversion and ensure isolation between software components
• Implement Quarkus DI to manage the life cycle of input and output ports

Who This Book Is For

This book is for software architects and Java developers who want to improve code maintainability and enhance productivity with an architecture that allows changes in technology without compromising business logic, which is precisely what hexagonal architecture does. Intermediate knowledge of the Java programming language and familiarity with Jakarta EE will help you to get the most out of this book.

Table of Contents

1. Why Hexagonal Architecture?
2. Wrapping Business Rules inside Domain Hexagon
3. Handling Behavior with Ports and Uses Cases
4. Creating Adapters to Interact with the Outside World
5. Creating Adapters to Interact with the Outside World
6. Building the Domain Hexagon
7. Building the Application Hexagon
8. Building the Framework Hexagon
9. Applying Dependency Inversion with Java Modules
10. Adding Quarkus to a Modularized Hexagonal Application
11. Leveraging CDI Beans to Manage Ports and Use Cases
12. Using RESTEasy Reactive to Implement Input Adapters
13. Persisting Data with Output Adapters and Hibernate Reactive
14. Setting Up Dockerfile and Kubernetes Objects for Cloud Deployment
15. Comparing Hexagonal Architecture with Layered Architecture
16. Using SOLID Principles with Hexagonal Architecture
17. Good Design Practices for Your Hexagonal Application

Davi Vieira is a software craftsman with a vested interest in the challenges faced by large enterprises in software design, development, and architecture. He has more than 10 years of experience constructing and maintaining complex, long-lasting, and mission-critical systems using object-oriented languages. He values the good lessons and the software development tradition left by others who came before him. Inspired by this software tradition, he develops and evolves his ideas.