A number of libraries have been written on top of ReactiveStreams that provide a functional-style API that makes asynchronous processing of a data stream very easy.
Notable examples of such libraries are RxJava 2 and Spring Reactor. ReactiveStreams provides a common API for all these libraries so that they are interoperable, and interoperable with any library that offers a ReactiveStreams API.
It is not uncommon that applications (especially REST applications) need to interact with a HTTP client to either consume or produce a stream of data. The typical example is an application making REST calls to a server and obtaining response content that needs to be transformed using ReactiveStreams APIs.
Another example is having a stream of data that you need to upload to a server using a REST call.
It’s evident that it would be great if there was a HTTP client that provides ReactiveStreams API, and this is what we have done with the Jetty ReactiveStreams HttpClient.
The Jetty ReactiveStreams HttpClient is a tiny wrapper over Jetty’s HttpClient; Jetty’s HttpClient was already fully non-blocking and already had full support for backpressure, so wrapping it with the ReactiveStreams API was fairly simple.
You can find detailed usage examples at the project page on GitHub.