Spring reactive web modules support both programming models--Annotation-based or the Functional-based programming model. Let's see how these models work on the server side:

• Annotations-based programming model: It is based on MVC annotations such as @Controller, @RestController, @RequestMapping, and many more. Annotations are supported by the Spring MVC framework for server-side programming for a web application.
• Functional programming model: It is a new paradigm of programming supported by the Spring 5 Framework. It is based on the Java 8 Lambda style routing and handling. Scala also provides the functional programming paradigm.

The following are the Maven dependencies that we have to add for a reactive web application based on Spring Boot:

    <parent> 
       <groupId>org.springframework.boot</groupId> 
       <artifactId>spring-boot-starter-parent</artifactId> 
       <version>2.0.0.M3</version> 
       <relativePath/> <!-- lookup parent from repository --> 
    </parent> 
 
    <properties> 
       <project.build.sourceEncoding>UTF-
        8</project.build.sourceEncoding> 
       <project.reporting.outputEncoding>UTF
        -8</project.reporting.outputEncoding> 
       <java.version>1.8</java.version> 
    </properties> 
 
    <dependencies> 
       <dependency> 
          <groupId>org.springframework.boot</groupId> 
          <artifactId>spring-boot-starter-webflux</artifactId> 
       </dependency> 
 
       <dependency> 
          <groupId>org.springframework.boot</groupId> 
          <artifactId>spring-boot-starter-test</artifactId> 
          <scope>test</scope> 
       </dependency> 
       <dependency> 
          <groupId>io.projectreactor</groupId> 
          <artifactId>reactor-test</artifactId> 
          <scope>test</scope> 
       </dependency> 
    </dependencies> 

As you can see in the preceding Maven configuration file for dependencies, we have added the spring-boot-starter-webflux and reactor-test dependencies to the application.

Let's create a reactive web application based on the Annotation-based programming model.