Book Image

Hands-On Reactive Programming with Reactor

By : Rahul Sharma
Book Image

Hands-On Reactive Programming with Reactor

By: Rahul Sharma

Overview of this book

Reactor is an implementation of the Java 9 Reactive Streams specification, an API for asynchronous data processing. This specification is based on a reactive programming paradigm, enabling developers to build enterprise-grade, robust applications with reduced complexity and in less time. Hands-On Reactive Programming with Reactor shows you how Reactor works, as well as how to use it to develop reactive applications in Java. The book begins with the fundamentals of Reactor and the role it plays in building effective applications. You will learn how to build fully non-blocking applications and will later be guided by the Publisher and Subscriber APIs. You will gain an understanding how to use two reactive composable APIs, Flux and Mono, which are used extensively to implement Reactive Extensions. All of these components are combined using various operations to build a complete solution. In addition to this, you will get to grips with the Flow API and understand backpressure in order to control overruns. You will also study the use of Spring WebFlux, an extension of the Reactor framework for building microservices. By the end of the book, you will have gained enough confidence to build reactive and scalable microservices.
Table of Contents (13 chapters)

Stream publisher

As we discussed in the previous chapter, the publisher is responsible for the generation of unbounded asynchronous events, and it pushes them to the associated subscribers. It is represented by the org.reactivestreams.Publisher interface, as follows:

public interface Publisher<T> {
    public void subscribe(Subscriber<? super T> s);

The interface provides a single subscribe method. The method is invoked by any party that is interested in listening to events published by the publisher. The interface is quite simple, and it can be used to publish any type of event, be it a UI event (like a mouse-click) or a data event.

Since the interface is simple, let's add an implementation for our custom FibonacciPublisher:

public class FibonacciPublisher implements Publisher<Integer> {
public void subscribe(Subscriber<? super Integer...