Guide to Spring 5 WebFlux

Overview

origin document link (opens new window)

Spring 5 includes Spring WebFlux, which provides reactive programming support for web applications. In this tutorial, we'll create a small reactive REST application using the reactive web components RestController and WebClient. We'll also look at how to secure our reactive endpoints using Spring Security.

Spring WebFlux Framework

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 (opens new window) – routing and handling in another tutorial.

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

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
    <version>2.2.6.RELEASE</version>
</dependency>

The latest spring-boot-starter-webflux (opens new window) can be downloaded from Maven Central.

Reactive REST Application

Now we'll build a very simple reactive REST EmployeeManagement application using Spring WebFlux:

• Use a simple domain model – Employee with an id and a name field
• Build a REST API with a RestController to publish Employee resources as a single resource and as a collection
• Build a client with WebClient to retrieve the same resource
• Create a secured reactive endpoint using WebFlux and Spring Security