Server Sent Events Java Client Implementation

SSE.java

package com.mirzaakhena.websocketdemo;

import java.util.concurrent.TimeUnit;
import javax.annotation.PostConstruct;
import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.WebTarget;
import javax.ws.rs.sse.InboundSseEvent;
import javax.ws.rs.sse.SseEventSource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.core.env.Environment;

@SpringBootApplication
public class SSE {

  Logger logger = LoggerFactory.getLogger(SSE.class);

  @Autowired
  private Environment env;

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

  private final String PROP_HANDSHAKING_URL = "app.handshaking_url";
  private final String PROP_HANDSHAKING_RETRY_IN_SECOND = "app.handshaking_retry_in_second";

  private WebTarget tut;
  private SseEventSource sse;

  @PostConstruct
  private void initAplikasi() {

    Client client = ClientBuilder.newClient();
    this.tut = client.target(env.getProperty(PROP_HANDSHAKING_URL));

    doHandshaking();
  }

  private void doHandshaking() {
    logger.info(String.format("Handshaking..."));
    sse = SseEventSource.target(this.tut).build();//
    sse.register(this::onMessage, this::onError, this::onComplete);
    sse.open();
  }

  private void onMessage(InboundSseEvent event) {
    logger.info(String.format("Message : %s | %s", event.getName(), event.readData()));
  }

  private void onError(Throwable t) {
    logger.error("Error : %s", t.getMessage());
  }

  private void onComplete() {
    logger.info(String.format("Connection Closed!"));
    try {
        int retry = Integer.parseInt(env.getProperty(PROP_HANDSHAKING_RETRY_IN_SECOND));
        Thread.sleep(retry * 1000L);
    } catch (InterruptedException e) {
    }
    doHandshaking();
  }

}



// application.properties
// -----------------------
// server.port = 8080
// app.handshaking_url = http://localhost:3000/handshake/0208
// app.handshaking_retry_in_second = 5

// pom.xml dependency
// <dependencies>
//   <dependency>
//     <groupId>org.springframework.boot</groupId>
//     <artifactId>spring-boot-starter-web</artifactId>
//   </dependency>
//   <dependency>
//     <groupId>org.glassfish.jersey.media</groupId>
//     <artifactId>jersey-media-sse</artifactId>
//     <version>2.26</version>
//   </dependency>
//   <dependency>
//     <groupId>org.glassfish.jersey.inject</groupId>
//     <artifactId>jersey-hk2</artifactId>
//     <version>2.26</version>
//   </dependency>
// </dependencies>