In the previous chapter, we saw how quickly an application can be created with just a few lines of code. In this chapter, we are going to embark upon a journey. We will build a social media application where users can upload pictures and write comments.

In this chapter, we will build the web layer for our social media application doing the following:

• Creating a reactive web application with Spring Initializr
• Learning the tenets of reactive programming
• Introducing Reactor types
• Switching from Apache Tomcat to Embedded Netty
• Comparing reactive Spring WebFlux against classic Spring MVC
• Showing some Mono/Flux-based endpoints
• Creating a reactive ImageService
• Creating a reactive file controller
• Showing how to interact with a Thymeleaf template
• Illustrating how going from async to sync can be easy, but the opposite is not