To launch things, we are going to take advantage of one of Spring Boot's hottest new features--Spring Framework 5's reactive support. The entire Spring portfolio is embracing the paradigm of reactive applications, and we'll focus on what this means and how we can cash in without breaking the bank.

Before we can do that, the question arises--what is a reactive application?

In simplest terms, reactive applications engage in the concept of non-blocking, asynchronous operations. Asynchronous means that the answer comes later, whether by polling or by an event pushed backed to us. Non-blocking means not waiting for a response, implying we may have to poll for the results. Either way, while the result is being formed, we don't hold up the thread, allowing it to service other calls.

The side effect of these two characteristics...