We've mentioned Reactive Streams with little detail. There is a spec for Reactive Streams (http://www.reactive-streams.org/), but it's important to understand that it is quite primitive. In fact, it's so primitive that it's not very effective for building applications. That may sound counterintuitive, but it wasn't written so much for end users as it was for framework developers. To build reactive applications, we'll use Project Reactor (http://projectreactor.io/), the core library that Spring Framework 5 uses for its reactive programming model.
To introduce Reactor's core types, we'll begin with the one we just saw in the previous section, Flux, and some code like this:
Flux.just("alpha", "bravo", "charlie"); ...
