Designing Hexagonal Architecture with Java

Book excerpt: A practical guide for software architects and Java developers to build cloud-native hexagonal applications using Java and Quarkus to create systems that are easier to refactor, scale, and maintain Key FeaturesLearn techniques to decouple business and technology code in an applicationApply hexagonal architecture principles to produce more organized, coherent, and maintainable softwareMinimize technical debts and tackle complexities derived from multiple teams dealing with the same code baseBook Description Hexagonal architecture enhances developers' productivity by decoupling business code from technology code, making the software more change-tolerant, and allowing it to evolve and incorporate new technologies without the need for significant refactoring. By adhering to hexagonal principles, you can structure your software in a way that reduces the effort required to understand and maintain the code. This book starts with an in-depth analysis of 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 by using ports and use cases in the Application hexagon, and make your software compatible with different technologies by employing adapters in the Framework hexagon. Moving on, you'll get your hands dirty developing a system based on a real-world scenario applying all the hexagonal architecture's building blocks. By creating a hexagonal system, you'll also understand how you can use Java modules to reinforce dependency inversion and ensure the isolation of each hexagon in the architecture. Finally, you'll get to grips with using Quarkus to turn your hexagonal application into a cloud-native system. By the end of this hexagonal architecture book, you'll be able to bring order and sanity to the development of complex and long-lasting applications. What you will learnFind out how to assemble business rules algorithms using the specification design patternCombine domain-driven design techniques with hexagonal principles to create powerful domain modelsEmploy adapters to make the system support different protocols such as REST, gRPC, and WebSocketCreate a module and package structure based on hexagonal principlesUse Java modules to enforce dependency inversion and ensure isolation between software componentsImplement Quarkus DI to manage the life cycle of input and output portsWho 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.