RocketMQ Quick Start

RocketMQ: Kafka: RocketMQ: Kafka: RocketMQ: Kafka: RocketMQ: Kafka: RocketMQ: Kafka: RocketMQ: Kafka: RocketMQ: Kafka: RocketMQ: Kafka: RocketMQ: Kafka: RocketMQ: Kafka: RocketMQ: Kafka MQ application scenarios, which let us know when MQ can be used and what problems can be solved, are introduced later: RocketMQ cluster deployment configuration; This article picks up where we left off with a quick RocketMQ primer.

How to use

1. Introduce RocketMQ-client

<dependency> <groupId>org.apache.rocketmq</groupId> <artifactId>rocketmq-client</artifactId> < version > 4.1.0 - incubating < / version > < / dependency >Copy the code

2. Writing Producer

 DefaultMQProducer producer = new DefaultMQProducer("producer_demo");
       // Specify the NameServer address
        producer.setNamesrvAddr("192.168.116.115:9876; 192.168.116.116:9876"); // Change it to your own

        /** * The Producer object must be initialized with the start method before being used, which can only be initialized once. Note that the start method cannot be called every time a message is sent
        producer.start();

        for (int i = 0; i < 997892; i++) {
            try {
                // Build the message
                Message msg = new Message("TopicTest" /* Topic */."TagA" /* Tag */,
                    ("Test RocketMQ" + i).getBytes(RemotingHelper.DEFAULT_CHARSET)
                );

                // Send a synchronization message
                SendResult sendResult = producer.send(msg);

                System.out.printf("%s%n", sendResult);
            } catch (Exception e) {
                e.printStackTrace();
                Thread.sleep(1000);
            }
        }


producer.shutdown();
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3. Write Consumer

/** ** Consumer Group, a very important concept, will be added later */
DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("consumer_demo");
// Specify the NameServer address. separated
consumer.setNamesrvAddr("192.168.116.115:9876; 192.168.116.116:9876"); // Change it to your own

/** * Sets whether the first Consumer starts at the head of the queue or at the end of the queue */
consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);

consumer.subscribe("TopicTest"."*");

consumer.registerMessageListener(new MessageListenerConcurrently() {

    @Override
    public ConsumeConcurrentlyStatus consumeMessage(List
       
         msgs, ConsumeConcurrentlyContext context)
        {
	try {
	    for(MessageExt msg:msgs){
		String msgbody = new String(msg.getBody(), "utf-8");
		System.out.println(" MessageBody: "+ msgbody);// Outputs the message content}}catch (Exception e) {
	    e.printStackTrace();
	    return ConsumeConcurrentlyStatus.RECONSUME_LATER; // Try again later
	}
	return ConsumeConcurrentlyStatus.CONSUME_SUCCESS; // Successful consumption}}); consumer.start(); System.out.printf("Consumer Started.%n");
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4, description,

Modify the value of NamesrvAddr according to your environment. For my cluster, please refer to RocketMQ Cluster Deployment Configuration. The RocketMQ console will display the multi-master, multi-slave and asynchronous replication cluster modes.

5. Use the RocketMQ console

The rocketmq-console-ng command is rocketmq-console-ng, and the MAVNE command is used to compile the JAR.

mvn clean package -Dmaven.test.skip=true
java -jar target/rocketmq-console-ng-1.0.0.jar
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Rocketmq-console-ng-1.0.0. jar\ boot-INF \classes\application.properties According to your own NamesrvAddr modified rocketmq. Config. NamesrvAddr values.

Direct start:

java -jar rocketmq-console-ng-1.0.0.jar
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6. Operation and observation

A good habit is to run Consumer first, then run Producer, and then watch from the RocketMQ-console-ng console

After running, it is true that the amount of data in broker-A plus the amount of data in Broker-B equals the amount of data we sent, and the number of slaves is the same as the number of masters, as follows:

Check the disk status of the two machines that sent these data as follows:Rocketmq1 occupies disk space

At this point, the RocketMQ Quickstart is over and to be continued…

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