Preface

Welcome to this journey into the heart of Spring! If you’ve ever stared at a blank IDE, wondering where to even begin when building a robust, scalable service, you’re not alone. The world of software development is full of grand ideas and ambitious goals, but turning those into well-structured, maintainable applications? That’s both an art and a science. This book is here to help you bridge that gap.

We will start with the foundations because great software is built on clarity. We’ll walk through dissecting requirements, distinguishing between functional and non-functional needs, and transforming them into domain objects and solid API contracts. It’s like laying down the blueprint before building a skyscraper—you wouldn’t want your application to topple at the first gust of real-world complexity.

Then, we’ll roll up our sleeves and get into the real magic: building services with Spring. How should interfaces interact with implementations? What’s a clean way to design services that will grow gracefully over time? We’ll answer these questions and propose a practical blueprint for creating new APIs and communicating seamlessly with other systems. And since security is a non-negotiable in today’s world, we’ll dive into user authentication, token creation, and validation using asymmetric keys.

Of course, no journey is complete without a few obstacles. We’ll face them head-on with testing—unit tests, integration tests, and end-to-end tests—ensuring that what we build is not just functional, but reliable. We’ll also explore event-driven architectures, discuss best practices for handling data integrations with SQL and NoSQL databases, and even build a fully-fledged Spring Cloud application.

But what happens when things go wrong? Because, let’s face it, they will. Services fail, networks break, and race conditions lurk in the shadows. That’s why we’ll also talk about designing for resilience: structuring configurations effectively, handling failures gracefully, and resolving concurrency issues like a seasoned architect.

Throughout this book, we’ll keep things practical. This isn’t an abstract tour of Spring 6’s features; it’s a hands-on guide to building applications that work in the real world—applications that scale, recover from failures, and integrate cleanly with the systems around them. We will work from a sample application that we call the HomeIt app, which connects landlords with tenants interested in renting properties.

So, grab your favorite beverage (coffee, tea, or whatever fuels your coding sessions), fire up your IDE, and let’s build something great together. Welcome to the world of Spring!