How to implement web Sockets in a spring boot application.

Posted By : Gursahib Singh | 30-Nov-2018

Java

Summary: In this blog,the implementation of web sockets in a spring boot application is explained.The steps to do the same includes, including the required dependencies, creating a Message Handling Controller followed by its configuration in the application.

Prerequisite:Knowledge of Java and Spring-boot framework.

What are Web Sockets: Websockets consists of protocal to create a fast two way channel connection between a web browser and a server.It is used to overcome limitiations of HTTP for allowing low latency communication between user and the web service.

Steps to implement web sockets in a spring boot application are:

1. The first step is to include the following dependencies in the pom.xml file.



<dependency>

   <groupId>org.springframework.boot</groupId>

   <artifactId>spring-boot-starter-websocket</artifactId>

</dependency>

<dependency>

   <groupId>org.webjars</groupId>

   <artifactId>webjars-locator</artifactId>

</dependency>

<dependency>

   <groupId>org.webjars</groupId>

   <artifactId>sockjs-client</artifactId>

   <version>1.0.2</version>

</dependency>

<dependency>

   <groupId>org.webjars</groupId>

   <artifactId>stomp-websocket</artifactId>

   <version>2.3.3</version>

</dependency>

<dependency>

   <groupId>org.webjars</groupId>

   <artifactId>bootstrap</artifactId>
   <version>3.3.7</version>        </dependency>

<dependency>

   <groupId>org.webjars</groupId>

   <artifactId>jquery</artifactId>

   <version>3.1.0</version>

</dependency>

2. The next step is to create Message Handling Controller for STOMP messaging. @Controller class can be used for routing the STOMP messages.

import org.springframework.messaging.handler.annotation.MessageMapping;
import org.springframework.messaging.handler.annotation.SendTo;
import org.springframework.stereotype.Controller;

@Controller
public class GreetingController {
   @MessageMapping("/hello")
   @SendTo("/topic/greetings")
   public Greeting greeting(HelloMessage message) throws Exception {
      Thread.sleep(1000); // simulated delay
      return new Greeting("Hello, " + message.getName() + "!");
   }
}

3. Now, the STOMP messaging is configured in the spring.For that, we need a WebSocketConfig class extending AbstractWebSocketMessageBrokerConfigurer class
as shown.

import org.springframework.context.annotation.Configuration;
import org.springframework.messaging.simp.config.MessageBrokerRegistry;
import org.springframework.web.socket.config.annotation.AbstractWebSocketMessageBrokerConfigurer;
import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;
import org.springframework.web.socket.config.annotation.StompEndpointRegistry;

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {
   @Override
   public void configureMessageBroker(MessageBrokerRegistry config) {
      config.enableSimpleBroker("/topic");
      config.setApplicationDestinationPrefixes("/app");
   }
   @Override
   public void registerStompEndpoints(StompEndpointRegistry registry) {
      registry.addEndpoint("/tutorialspoint-websocket").withSockJS();
   }
}

The @EnableWebSocketMessageBroker annotaion configures the web socket message broker for STOMP endpoints.

4. The code for the spring boot main application file is:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

Conclusion:

This is how web socket can be implemented in a spring boot application.The web sockets help in achieving the interaction between the web client and web server with lower over heads and facilitates real time data transfer.