操作018：Stream Queue

一、启用插件

说明：只有启用了Stream插件，才能使用流式队列的完整功能

在集群每个节点中依次执行如下操作：

# 启用Stream插件
rabbitmq-plugins enable rabbitmq_stream

# 重启rabbit应用
rabbitmqctl stop_app
rabbitmqctl start_app

# 查看插件状态
rabbitmq-plugins list

二、负载均衡

在文件/etc/haproxy/haproxy.cfg末尾追加：

frontend rabbitmq_stream_frontend
bind 192.168.200.100:33333
mode tcp
default_backend rabbitmq_stream_backend

backend rabbitmq_stream_backend
mode tcp
balance roundrobin
server rabbitmq1 192.168.200.100:5552 check
server rabbitmq2 192.168.200.150:5552 check
server rabbitmq3 192.168.200.200:5552 check

三、Java代码

1、引入依赖

Stream 专属 Java 客户端官方网址：https://github.com/rabbitmq/rabbitmq-stream-java-client

Stream 专属 Java 客户端官方文档网址：https://rabbitmq.github.io/rabbitmq-stream-java-client/stable/htmlsingle/

<dependencies>
    <dependency>
        <groupId>com.rabbitmq</groupId>
        <artifactId>stream-client</artifactId>
        <version>0.15.0</version>
    </dependency>

    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.30</version>
    </dependency>
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.2.3</version>
    </dependency>
</dependencies>

2、创建Stream

说明：不需要创建交换机

①代码方式创建

Environment environment = Environment.builder()
        .host("192.168.200.100")
        .port(33333)
        .username("atguigu")
        .password("123456")
        .build();

environment.streamCreator().stream("stream.atguigu.test2").create();

environment.close();

②ManagementUI创建

3、生产者端程序

①内部机制说明

[1]官方文档

Internally, the Environment will query the broker to find out about the topology of the stream and will create or re-use a connection to publish to the leader node of the stream.

翻译：

在内部，Environment将查询broker以了解流的拓扑结构，并将创建或重用连接以发布到流的 leader 节点。

[2]解析

在 Environment 中封装的连接信息仅负责连接到 broker
Producer 在构建对象时会访问 broker 拉取集群中 Leader 的连接信息
将来实际访问的是集群中的 Leader 节点
Leader 的连接信息格式是：节点名称:端口号

[3]配置

为了让本机的应用程序知道 Leader 节点名称对应的 IP 地址，我们需要在本地配置 hosts 文件，建立从节点名称到 IP 地址的映射关系

②示例代码

Environment environment = Environment.builder()
        .host("192.168.200.100")
        .port(33333)
        .username("atguigu")
        .password("123456")
        .build();

Producer producer = environment.producerBuilder()
        .stream("stream.atguigu.test")
        .build();

byte[] messagePayload = "hello rabbit stream".getBytes(StandardCharsets.UTF_8);

CountDownLatch countDownLatch = new CountDownLatch(1);

producer.send(
        producer.messageBuilder().addData(messagePayload).build(),
        confirmationStatus -> {
            if (confirmationStatus.isConfirmed()) {
                System.out.println("[生产者端]the message made it to the broker");
            } else {
                System.out.println("[生产者端]the message did not make it to the broker");
            }

            countDownLatch.countDown();
        });

countDownLatch.await();

producer.close();

environment.close();

4、消费端程序

Environment environment = Environment.builder()
        .host("192.168.200.100")
        .port(33333)
        .username("atguigu")
        .password("123456")
        .build();

environment.consumerBuilder()
        .stream("stream.atguigu.test")
        .name("stream.atguigu.test.consumer")
        .autoTrackingStrategy()
        .builder()
        .messageHandler((offset, message) -> {
            byte[] bodyAsBinary = message.getBodyAsBinary();
            String messageContent = new String(bodyAsBinary);
            System.out.println("[消费者端]messageContent = " + messageContent + " Offset=" + offset.offset());
        })
        .build();

四、指定偏移量消费

1、偏移量

2、官方文档说明

The offset is the place in the stream where the consumer starts consuming from. The possible values for the offset parameter are the following:

OffsetSpecification.first(): starting from the first available offset. If the stream has not been truncated, this means the beginning of the stream (offset 0).

OffsetSpecification.last(): starting from the end of the stream and returning the last chunk of messages immediately (if the stream is not empty).

OffsetSpecification.next(): starting from the next offset to be written. Contrary to OffsetSpecification.last(), consuming with OffsetSpecification.next() will not return anything if no-one is publishing to the stream. The broker will start sending messages to the consumer when messages are published to the stream.

OffsetSpecification.offset(offset): starting from the specified offset. 0 means consuming from the beginning of the stream (first messages). The client can also specify any number, for example the offset where it left off in a previous incarnation of the application.

OffsetSpecification.timestamp(timestamp): starting from the messages stored after the specified timestamp. Note consumers can receive messages published a bit before the specified timestamp. Application code can filter out those messages if necessary.

3、指定Offset消费

Environment environment = Environment.builder()
        .host("192.168.200.100")
        .port(33333)
        .username("atguigu")
        .password("123456")
        .build();

CountDownLatch countDownLatch = new CountDownLatch(1);

Consumer consumer = environment.consumerBuilder()
        .stream("stream.atguigu.test")
        .offset(OffsetSpecification.first())
        .messageHandler((offset, message) -> {
            byte[] bodyAsBinary = message.getBodyAsBinary();
            String messageContent = new String(bodyAsBinary);
            System.out.println("[消费者端]messageContent = " + messageContent);
            countDownLatch.countDown();
        })
        .build();

countDownLatch.await();

consumer.close();