Spring WebFlux internally uses Project Reactor and its publisher implementations, Flux and Mono.

The new framework supports two programming models:

Annotation-based reactive components

Functional routing and handling

We'll focus on the annotation-based reactive components, as we already explored the functional style – routing and handling in another tutorial.

3. Dependencies

Let's start with the spring-boot-starter-webflux dependency, which pulls in all other required dependencies:

spring-boot and spring-boot-starter for basic Spring Boot application setup

spring-webflux framework

reactor-core that we need for reactive streams and also reactor-netty

https://tech.trivago.com/post/2021-03-16-java-reactive-programming-real-world/