[JavaForFun] /

package de.spring.stomp.services.impl;

import java.time.LocalDateTime;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationListener;
import org.springframework.messaging.simp.SimpMessagingTemplate;
import org.springframework.messaging.simp.broker.BrokerAvailabilityEvent;
import org.springframework.stereotype.Service;

import de.spring.stomp.services.RestGreetingService;

@Service("restGreetingService")
public class RestGreetingServiceImpl
                implements RestGreetingService, ApplicationListener<BrokerAvailabilityEvent> {
        private final SimpMessagingTemplate template;
        
        private volatile boolean isBrokerAvailable = true;

    @Autowired
    public RestGreetingServiceImpl(SimpMessagingTemplate template) {
        this.template = template;
    }

        @Override
        public void doGreetings(String greeting) {
                String text = "[" + LocalDateTime.now() + "]:" + greeting;
                
                if (isBrokerAvailable) {
                        // STOMP clients subscribed to /topic/greeting will receive the data sent by the convertAndSend method.
                        template.convertAndSend("/topic/greeting", text);
                }
        }

        @Override
        public void onApplicationEvent(BrokerAvailabilityEvent event) {
                // Components using the SimpMessagingTemplate should subscribe to this event
                // and avoid sending messages at times when the broker is not available.
                // In any case they should be prepared to handle MessageDeliveryException
                // when sending a message.
                isBrokerAvailable = event.isBrokerAvailable();
        }
}