NetworkEventSimulator.java

package learningspringboot;

import java.time.LocalDateTime;
import java.util.Random;

import org.springframework.boot.actuate.metrics.CounterService;
import org.springframework.jms.core.JmsTemplate;
import org.springframework.scheduling.annotation.Scheduled;

public class NetworkEventSimulator {

	// tag::simulator[]
	final private JmsTemplate jmsTemplate;
	final private String destination;
	final private CounterService counterService;

	public NetworkEventSimulator(JmsTemplate jmsTemplate, String destination,
								 CounterService counterService) {
		this.jmsTemplate = jmsTemplate;
		this.destination = destination;
		this.counterService = counterService;
	}
	// end::simulator[]

	// tag::simulateactivity[]
	@Scheduled(fixedRate = 1000L)
	public void simulateActivity() {
	// end::simulateactivity[]

		Random random = new Random();

		String hostname;
		switch (random.nextInt(3)) {
			case 0: hostname = "router101"; break;
			case 1: hostname = "multiplex205"; break;
			default: hostname = "switch1143"; break;
		}

		Severity severity;
		switch (random.nextInt(4)) {
			case 0: severity = Severity.UP; break;
			case 1: severity = Severity.DEGRADED; break;
			case 2: severity = Severity.JEOPARDY; break;
			default: severity = Severity.DOWN; break;
		}
		// tag::produced[]
		Alarm event = new Alarm(hostname, LocalDateTime.now(),
				severity);
		jmsTemplate.convertAndSend(destination, event);
		counterService.increment("messages.total.produced");
		counterService.increment("messages." + event.getHostname() + ".produced");
	}
	// end::produced[]

}