Rahul Sharma - Hands-On Reactive Programming with Reactor: Build reactive and scalable microservices using the Reactor framework

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First published: September 2018

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ISBN 978-1-78913-579-4

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Rahul Sharma is a seasoned Java developer with around 13 years' experience in Java/J2EE applications. He has worked at companies ranging from enterprises to start-ups. Being an open source enthusiast, he has contributed to various projects, including Apache Crunch . He is currently working with a Java framework, Project Reactor.

Suchit Khanna is a seasoned developer, cricket enthusiast, and an avid traveler. He has worked for more than a decade in helping to build maintainable and scalable enterprise systems. When he's not writing code, he's most likely playing cricket or traveling with his better half.

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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 on the Publisher and Subscriber APIs. The first four chapters will help you to understand Reactive Streams and the Reactor framework. The following four chapters use Reactor to build a microservices SpringWebFlux extension to build REST-based web services. They demonstrate the concepts of the flow, backpressure, and execution models. You will gain an understanding of how to use two reactive composable APIs, Flux and Mono, which are used extensively to implement Reactive Extensions. In the final two chapters, you will gain an understanding of Reactive Streams and the Reactor framework.

The chapters explain the most important parts and build simple programs to establish a foundation. By the end of the book, you will have gained enough confidence to build reactive and scalable microservices.

For anyone with a basic understanding of Java's fundamental concepts, and how to develop event-driven and data-driven applications easily with Reactor, this book is for you a step-by-step guide to getting you up and running with Reactive Streams and the Reactor framework.

, Getting Started with Reactive Streams , explains the Reactive Streams API and introduces the reactive paradigm and its benefits. The chapter also introduces Reactor as an implementation of Reactive Streams.

, The Publisher and Subscriber APIs in a Reactor , explains the Producer and Subscriber APIs and the corresponding Flux and Mono implications of Reactor. It also discusses use cases of Flux and Mono and the respective Sinks. We will also look into Hot and Cold variants of the components.

, Data and Stream Processing , tackles how we can process data generated by a Publisher before it gets consumed by a Subscriber, the possible operations available, and combining them to build a robust stream-processing pipeline. Stream processing also involves converting, pivoting, and aggregating data, and then generating new data.

, Processors , introduces the out-of-the-box processors available in Reactor. Processors are special Publishers, which are also Subscribers, and it is quite important to understand why we need them before jumping into putting one into practice.