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)

Filtering data

Let's start with the most simple operator for selecting data. There are different analogies of data filtration, as follows:

  • Select or reject data based on a given condition
  • Select or reject a subset of the generated data

The preceding information is depicted in the following diagram:

The filter() operator

The filter() operator enables selection of the data on the passed condition. The API takes a Boolean predicate, which is evaluated for every emitted value, in order to determine whether it is selected. Filtering is quite common. Let's suppose that we want to select dates based on a month range, or we want to select employee data based on employee IDs. In those cases, the Boolean predicate passed...