The Spring team has kept the same annotations for both Spring MVC and Spring WebFlux as these annotations are non-blocking. Therefore, you can use the same annotations we have used in previous chapters for creating REST controllers. There, the annotation runs on Reactive Core and provides a non-blocking flow. However, you, as the developer, have the responsibility of maintaining a fully non-blocking flow and maintaining the Reactive chain (pipeline). Any blocking calls in a Reactive chain would convert the Reactive chain into a blocking call.

Let's create a simple REST controller that supports non-blocking and Reactive calls: