Can I use the Event Bus to decouple all of the application layers? I m trying to use the clean architecture. Normally the decoupling is made by a boundaries interfaces, I have seen some examples using RX observers for that. The question is can i use Event Bus to decouple the layers? and can the event bus handle such a job?
Event Bus is perfect for cross-cutting activities so you don't need to pass trough a middle layer to deliver an event if you don't need to.
For clean/onion/multi-layer architecture you don't need Event Bus but clear contracts between the layers i.e. boundary interfaces. They may or may not use RX.
You can fully decouple modules using on Event Bus with no interfaces whatsoever and then all components will be extremely decoupled, however it will become a hell to debug, maintain and super difficult to do anything meaningful :) So some kind of contract is always a good idea even when using Event Bus.
Combining Reactive Programming and Event Bus you can create highly decoupled event driven pico services bounded by some contracts around your Event Bus in order to improve clarity of the event/command/data flow.
I am personally using and working on RxHub which was born exactly from the need of passing cross-cutting events and easy data-flow operators chaining.