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)

Scheduler

Reactor executes all operations using one of the schedulers. A Reactor scheduler does not belong to the java.util.concurrent API. The Java concurrent API is quite low-level, where we can initiate and control task execution. On the other hand, all tasks in a Reactor chain are executed by the Reactor engine. Consequently, we do not need a low-level API to manage task execution. Instead, Reactor offers a declarative model, which we can use to configure a Scheduler and alter the behavior of the chain execution.

Before we start to configure Reactor, let's first determine the default execution model. By default, Reactor is mostly single-threaded. The publisher and subscriber do not create additional threads for their execution. All life cycle hooks, and most operators, perform single-threaded execution. Before we jump ahead, let's build some code to validate this...