Controllers are the integration point between models and views in the MVC paradigm. They act like the glue that binds together everything while taking care of business logic execution and routing. The following Maven starter dependency needs to be added to enable Spring WebFlux:

<dependencies>
   ...
   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-webflux</artifactId>
   </dependency>
</dependencies>

The preceding dependency will import the Reactive Streams, Spring, and Netty dependencies to enable successful writing of Servlet-based web applications using Spring.