RSocket, a powerful messaging protocol, is a perfect fit for building reactive microservices in a Spring Boot environment. This article will guide you through integrating RSocket with Spring Boot using both Maven and Gradle build systems. We’ll explore adding the necessary dependencies, configuration options, and basic usage examples.

Getting Started: Adding RSocket

Spring Boot makes adding RSocket functionality a breeze. Here’s how to include it in your project:

Maven:

1. Add the spring-boot-starter-rsocket dependency to your pom.xml file:

XML

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-rsocket</artifactId>
</dependency>

Gradle:

2. Include the same dependency in your build.gradle file:

Groovy

dependencies {
  implementation 'org.springframework.boot:spring-boot-starter-rsocket'
}

With these dependencies in place, Spring Boot auto-configures RSocket, enabling you to create servers and clients.

Configuration Options

Spring provides flexibility in configuring your RSocket setup. Here are some key options:

• Ports: Use application properties like server.rsocket.port and client.rsocket.port to define server listening port and client connection port.
• Message Serialization: Spring supports various serialization formats like JSON and CBOR. You can configure this with properties like rsocket.messaging-codec or annotations like @RSocketMessageCodec.

Spring Annotations:

• @RSocketController: Annotate classes to define RSocket controllers that handle incoming requests.
• @MessageMapping: Annotate methods within controllers to map incoming messages to specific handlers.
• @Payload: Annotate method arguments to indicate they receive the message payload.

Building an RSocket Server

Let’s create a simple RSocket server that echoes back received messages:

Java

@SpringBootApplication
@RSocketController
public class EchoServer {

  @MessageMapping("echo")
  public String echo(@Payload String message) {
    return "Echo: " + message;
  }

  public static void main(String[] args) {
    SpringApplication.run(EchoServer.class, args);
  }
}

This server exposes an endpoint named “echo” that accepts string messages. The echo method receives the message payload and returns an echoed response.

Using an RSocket Client

To interact with the server, we can create a simple RSocket client:

Java

@SpringBootApplication
public class EchoClient {

  @Autowired
  private RSocketRequester rSocketRequester;

  public static void main(String[] args) {
    SpringApplication.run(EchoClient.class, args);
    EchoClient client = new EchoClient(ApplicationContextProvider.getApplicationContext().getBean(RSocketRequester.class));
    client.sendEchoRequest("Hello, RSocket!");
  }

  private Mono<Void> sendEchoRequest(String message) {
    return rSocketRequester
        .route("echo")
        .data(message)
        .send()
        .and(r -> r.receive().mono().subscribe(payload -> System.out.println("Received: " + payload.getData())));
  }
}

This client injects the RSocketRequester bean and uses it to route a message to the server’s “echo” endpoint. The client then subscribes to the response stream and prints the received message.

Remember: Run the server first, then the client, to establish the connection.

Conclusion

This article provided a basic introduction to integrating RSocket with Spring Boot using Maven and Gradle. With Spring’s abstractions and RSocket’s reactive nature, you can build robust and scalable microservices. Explore the Spring RSocket documentation (https://spring.io/blog/2020/03/09/getting-started-with-rsocket-spring-boot-client) for more advanced use cases and configuration options. Start building your next reactive application with the power of Spring Boot and RSocket!