@iamszabo Do I understand correctly that WebFlux doesn’t use Rx at all and instead, invents its own copy of it?

They use Reactor which is a spring project but I think you can plug in Rx if you want to use that.

Not sure how since the types would not be compatible

It uses Reactive Streams so anything that implements that can be used. https://docs.spring.io/spring-framework/docs/5.0.x/spring-framework-reference/web-reactive.html#webflux-reactive-api

Ah ok

The cornerstone of WebFlux is indeed Reactive Streams, which allows us to adapt to any non-blocking API : RxJava 1, RxJava 2,

CompletableFuture

, Akka, Coroutines. Reactor is leveraging most Reactive extensions conventions but using RxJava was not possible for us.

Flux

+

Mono

types is different from RxJava 2 type strategy, we are Java 8+, need to garantee API stability from a Pivotal POV, we need specific features like context that RxJava does not have, etc. Also keep in mind that Reactor is a co-production between Stéphane Maldini (Pivotal) and David Karnok (RxJava lead). Last but not least, Reactor is not just Reactor Core, Reactor Netty and other parts of the ecosystem.