Quarkus: Support Spring 5 Reactive (WebFlux)

[ebullient]

Description
Spring 5 Reactive support is based on WebFlux, which is a Java8-based reimplementation of RxJava. From a general Spring implementation perspective, the reactive workloads based on WebFlux can drop or bypass interaction with Tomcat to go right to Netty or Undertow, which could map nicely (with Quarkus undertow).

Reference:
https://docs.spring.io/spring-framework/docs/5.0.0.M1/spring-framework-reference/html/web-reactive.html

[kenfinnigan]

I know @cescoffier has done some thinking on this, so not sure what the latest is.

But I believe the idea is we'd use reactive types that can be mapped to WebFlux, but not directly use WebFlux

[ebullient]

That's a possibility, sure. Point is, from an application developer's POV, they should be able to follow Spring docs & guides for writing WebFlux / Spring 5 Reactive applications, and it should work (within confines of what is possible with Quarkus re: dynamic behavior @ runtime)

[emmanuelbernard]

@ebullient I'm not sure WebFlux is used that much. So that would be a lot of effort for something not necessarily mainstream vs asking users to embrace Quarkus/Vert.x reactive web way (which might have even more usages)

[ebullient]

If a Spring developer follows the Spring way.. they will land on WebFlux. We should be able to get it working, as the snowdrop impl can put Vert.x underneath the WebFlux impl ..