Processor

A Processor represents a processing stage--which is both a Subscriber and a Publisher, and MUST obey the contracts of both. A of can be chained by connecting a Publisher and Subscriber:

    public interface Processor<T, R> extends Subscriber<T>, 
      Publisher<R> {
    }

Reactor has two implementations for Publisher--Flux and Mono. Flux can emit 0...N events, whereas, Mono is for a single event (0...1). Flux is required when many data elements or a list of values is transmitted as Streams.