Reactive Programming with Spring Boot and Spring WebFlux

Reactive Programming and its functional incarnation reactive functional programming are declarative programming paradigms that with the advent of reactive extensions for JavaScript such as RxJS have become immensely popular. The JavaScript event loop and the run-to-completion behaviour it entails as well as Node.js’s non-blocking I/O calls lend themselves to an event-driven programming style that deals with asynchronous behaviour where both number and frequency of events aren’t known beforehand.

Reactor is a library that introduces this paradigm to Java. Spring WebFlux is a framework that allows you to write Spring and Spring Boot web applications in this declarative manner. Vladimir Fomene has published an article at Auth0 that provides an in-depth introduction to Spring WebFlux and how to use it.