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)

Generating errors

Before we try to handle errors, let's first try to raise a few. In Java ecosystems, error conditions are raised by throwing exceptions. Exceptions can be raised under the following conditions:

  • The producer can throw an exception while generating the next value.
  • The subscriber can throw an exception while processing the next value or subscription event, or in any operators.

In all of the preceding conditions, there must be an effective procedure for handling the error raised. Reactive Streams prescribe the error event for the same purpose. The specification states that a producer should raise an error event, instead of throwing an exception. However, the specification does not discuss exceptions raised while processing events in the subscriber. Let's start to work on our Fibonacci series, to understand how error handling happens in Reactor:

    @Test...