In the Chapter 4, Authentication Using CAS and JAAS, we went through the reactive Spring WebFlux web application framework in detail. We also looked into a lot of the reactive programming support provided by the Spring Framework and other Spring modules. Knowingly or unknowingly, we created a reactive REST API in the previous chapter's example sections. We used a handler and router mechanism for creating a RESTful application and also secured it using the BASIC authentication mechanism.
We saw the workings of WebClient (a reactive way of calling REST APIs, as opposed to using a blocking RestTemplate) and WebTestClient (a reactive way of writing test cases). We also saw the workings of Spring Data in a reactive way using MongoDB as the persistent store.
We will not go through these aspects here; we will only mention that, if you wish, you can...
