11.2.2 Adding Reactor dependencies

To get started with Reactor, add the following dependency to the project build:

<dependency>
    <groupId>io.projectreactor</groupId>
    <artifactId>reactor-core</artifactId>
</dependency>

Reactor also provides some great testing support. You’re going to write a lot of tests around your Reactor code, so you’ll definitely want to add the next dependency to your build:

<dependency>
    <groupId>io.projectreactor</groupId>
    <artifactId>reactor-test</artifactId>
    <scope>test</scope>
</dependency>

I’m assuming that you’re adding these dependencies to a Spring Boot project, which handles dependency management for you, so there’s no need to specify the <version> element for the dependencies. But if you want to use Reactor in a non–Spring Boot project, you’ll need to set up Reactor’s BOM (bill of materials) in the build. The following dependency management entry adds Reactor’s 2020.0.4 release to the build:

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>io.projectreactor</groupId>
      <artifactId>reactor-bom</artifactId>
      <version>2020.0.4</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

The examples we’ll work with in this chapter are standalone and unrelated to the Taco Cloud projects we’ve been working with. Therefore, it may be best to create a fresh new Spring project with the Reactor dependencies in the build and work from there.

Now that Reactor is in your project build, you can start creating reactive pipelines with Mono and Flux. For the remainder of this chapter, we’ll walk through several operations offered by Mono and Flux.