Reliability ActiveMQ-- message

Persistent (PERSISTENT)

• messageProducer.setDeliverMode (DeliverMode.NON_PERSISTENT); non-persistent: when the server is down, the message does not exist
• messgageProducer.setDeliveryMode (DeliveryMode.PERSISTENT); Persistence: When the server is down, the message remains.

Queue (queue) persistence:

The default queue is persistent mode, which ensure that these messages are transmitted only once and successfully used once. For these messages, reliability is a prime consideration.

Another important aspect is to ensure the reliability of a persistent message to the target, message service before transmitting them to the consumer does not lose the messages.

Theme (topic) persistence:
Consumer Code:

package pres.zhang.persistent;

import org.apache.activemq.ActiveMQConnectionFactory;

import javax.jms.*;
import java.io.IOException;

public class Topic_Consumer {
    public static final String ACTIVEMQ_URL = "tcp://localhost:61616";
    public static final String TOPIC_NAME = "topic_acton";

    public static void main(String[] args) throws JMSException, IOException {
        //1.创建连接工厂,按照给定的url地址，采用默认用户名和密码
        ActiveMQConnectionFactory activeMQConnectionFactory = new ActiveMQConnectionFactory(ACTIVEMQ_URL);
        //2.通过连接工厂，获得连接connection，并启动访问
        Connection connection = activeMQConnectionFactory.createConnection();
        //connection.start();

        //设置订阅用户
        connection.setClientID("test");

        //3.创建回话session
        //两个参数 1.事务  2.签收
        Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        //4.创建目的地（具体是队列还是主题topic）
        Topic topic = session.createTopic(TOPIC_NAME);

        //创建持久化的订阅 参数：1.主题 2.备注
        TopicSubscriber topicSubscriber = session.createDurableSubscriber(topic, "remard");

        //发布订阅
        connection.start();
        Message message = topicSubscriber.receive();

        while (null != message){
            TextMessage textMessage = (TextMessage) message;
            System.out.println("收到的持久化topic：" + ((TextMessage) message).getText());
            //继续监听
            message = topicSubscriber.receive(1000L);
        }

        session.close();
        connection.close();
    }
}

Producers Code:

package pres.zhang.persistent;

import org.apache.activemq.ActiveMQConnectionFactory;

import javax.jms.*;

public class Topic_Produce {
    public static final String ACTIVEMQ_URL = "tcp://localhost:61616";
    public static final String TOPIC_NAME = "topic_acton";

    public static void main(String[] args) throws JMSException {
        //1.创建连接工厂,按照给定的url地址，采用默认用户名和密码
        ActiveMQConnectionFactory activeMQConnectionFactory = new ActiveMQConnectionFactory(ACTIVEMQ_URL);
        //2.通过连接工厂，获得连接connection，并启动访问
        Connection connection = activeMQConnectionFactory.createConnection();
        //connection.start();

        //3.创建回话session
        //两个参数 1.事务  2.签收
        Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        //4.创建目的地（具体是队列还是主题topic）
        Topic topic = session.createTopic(TOPIC_NAME);
        //创建消息的生产者
        MessageProducer messageProducer = session.createProducer(topic);
        //通过使用messageProducer生产3条消息发送到MQ的队列里面

        //设置持久化主题
        messageProducer.setDeliveryMode(DeliveryMode.PERSISTENT);
        //因为设置持久化主题，所以connect.start()在这里调用
        connection.start();
        for (int i = 0; i < 3; i++) {
            //7.创建消息
            TextMessage textMessage = session.createTextMessage("TOPIC_NAME---" + i);//可以理解为字符串
            //8.通过messageProducer发送给MQ
            messageProducer.send(textMessage);
        }
        //9.关闭资源
        messageProducer.close();
        session.close();
        connection.close();;
        System.out.println("消息发布到TOPIC完成！");
    }
}

Test: run the consumer side, thematic subscription:

Display has an active subscriber, because there is no message to the consumer spending, so the program has been listening. We close the program, changes are as follows:

Because our program is terminated, so the display to the offline field, but we have successfully subscribed.

Now run news producers:

Message sent successfully. We run again Consumers:
Console Print:

收到的持久化topic：TOPIC_NAME---0
收到的持久化topic：TOPIC_NAME---1
收到的持久化topic：TOPIC_NAME---2

Successfully received the message, because we have subscribed to the topic.

to sum up:

1. Must first run a consumer, equal to register with the MQ, similar to what we subscribed to this topic.
2. Message producer sends then run
3. At this point, regardless of whether the consumer online, will receive, not online, then connect the next time, I will never received the message receives down.