In this chapter, we highlighted the requirements for cost-efficient IT solutions that often arise nowadays. We described why and how big companies such as Amazon failed to force old architectural patterns to work smoothly in current cloud-based distributed environments.

We also established the need for new architectural patterns and programming techniques to fulfill the ever-growing demand for convenient, efficient, and intelligent digital services. With the Reactive Manifesto, we deconstructed and comprehended the term reactivity and also described why and how elasticity, resilience, and message-driven approaches help to achieve responsiveness, probably the primary non-functional system requirement in the digital era. Of course, we gave examples in which the reactive system shines and easily allows businesses to achieve their goals.

In this chapter, we have highlighted a clear distinction between a reactive system as an architectural pattern and reactive programming as a programming technique. We described how and why these two types of reactivity play well together and enable us to create highly efficient die-hard IT solutions.

To go deeper into Reactive Spring 5, we need to gain a solid understanding of the reactive programming basement, learning essential concepts and patterns that determine the technique. Therefore, in the next chapter, we will learn the essentials of reactive programming, its history, and the state of the reactive landscape in the Java world.