Book Image

Designing Hexagonal Architecture with Java - Second Edition

By : Davi Vieira
Book Image

Designing Hexagonal Architecture with Java - Second Edition

By: Davi Vieira

Overview of this book

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, the question arises — how to develop software capable of handling a high level of unpredictability. With this question in mind, this book explores how the 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 by uncovering the secrets of the hexagonal architecture’s building blocks, such as entities, use cases, ports, and adapters. You’ll learn how 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’ll learn about the differences between a 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.
Table of Contents (24 chapters)
1
Part 1: Architecture Fundamentals
7
Part 2: Using Hexagons to Create a Solid Foundation
12
Part 3: Becoming Cloud-Native
18
Part 4: Hexagonal Architecture and Beyond

Building the Framework Hexagon

When building a hexagonal application, the last step consists of exposing the application features by connecting input adapters to input ports. Also, if there is any need to get data from, or persist it inside, external systems, then we need to connect output adapters to output ports. The Framework hexagon is the place where we assemble all the adapters required to make the hexagonal system.

We first created the domain model using things including entities, value objects, and specifications in the Domain hexagon. Then, in the Application hexagon, we expressed the user’s intent using use cases and ports. Now, in the Framework hexagon, we have to employ adapters to expose system features and define which technologies will be used to enable such features. After assembling the Domain, Application, and Framework hexagons, we will have an architecture resembling the following figure:

Figure 8.1 – Domain, Application, and Frameworks hexagons assembled

Figure 8.1 – Domain, Application...