微服务系列笔记之Broker模式入门篇

不忘初心,砥砺前行

作者 | 陌无崖

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导语

API模式笔记告一段了,这篇文章总结了Micro中的消息订阅模式,在之前的系列文章中讲解了RabbitMQ消息队列,使用的是原生代码进行编写,在Micro中,其实为我们封装了RabbitMQ消息队列,不仅仅是RabbitMQ还有NATs作为消息中间件,称之为broker模式,在这篇文章中我们进行一个简单的发布与订阅模式的介绍。

入门案例介绍

首先建立如下目录

编写我们的main.go,首先,定义一个待发布的主题和一个broker,使用broker需要导入包。

import "github.com/micro/go-micro/broker"
var (
    // 定义一个待发布的主题
    topic = "mu.micro.book.topic.payment.done"
    b     broker.Broker
)

编写一个发布消息的函数如下,在代码中broker.Message是一个结构体,我们将要发送的消息需要存入该结构体中,最后使用broker.Publish发布消息。

func pub() {
    // 该Ticker包含一个通道字段,并会每隔时间段d就向该通道发送当时的时间。
    // 它会调整时间间隔或者丢弃tick信息以适应反应慢的接收者。如果d<=0会panic。关闭该Ticker可以释放相关资源。
    tick := time.NewTicker(time.Second)
    i := 0
    for range tick.C {
        msg := &broker.Message{
            Header: map[string]string{
                "id": fmt.Sprintf("%d", i),
            },
            Body: []byte(fmt.Sprintf("%d:%s", i, time.Now().String())),
        }
        log.Infof(broker.String())
        // 发布消息
        if err := broker.Publish(topic, msg); err != nil {
            log.Infof("[pub] Message publication failed: %v", err)
        } else {
            fmt.Println("[pub] Message published: ", string(msg.Body))
        }
        i++
    }
}

有发布消息的函数,肯定就有接收消息的函数如下,通过broker.Subscribe完成主题的订阅。其他的调用见名知义,不再详细介绍。

func sub() {
    // 订阅消息并接收
    _, err := broker.Subscribe(topic, func(p broker.Event) error {
        log.Info("[sub] Received Body: %s,Header: %s\n", string(p.Message().Body), p.Message().Header)
        return nil
    })
    if err != nil {
        fmt.Println(err)
    }
}

编写我们的main函数,这里需要注意导入相关的包

"github.com/micro/go-micro/config/cmd"
"github.com/micro/go-micro/util/log"

使用Init进行初始化然后开始连接,开启两个协程进行收发消息,使用time.After()设置过期时间,当时间到时,并向当前通道发送事件,结束主线程。防止主线程提前结束。如果这一点不懂请移步我的博客看关于进程线程和Go协程总结这篇文章。

func main() {
    cmd.Init()
    if err := broker.Init(); err != nil {
        log.Fatalf("broker.Init() error: %v", err)
    }
    if err := broker.Connect(); err != nil {
        log.Fatalf("broker.Connect() error: %v", err)
    }

    go pub()
    go sub()

    <-time.After(time.Second * 20)
}

看到这里是不是觉得很简单,测试一番,结果如下

PS F:\micolearn\day02\mico-broker\basic> go run main.go
2019/08/12 16:28:37 http
[pub] Message published:  0:2019-08-12 16:28:37.388162 +0800 CST m=+1.024290401
2019/08/12 16:28:37 [sub] Received Body: %s,Header: %s
0:2019-08-12 16:28:37.388162 +0800 CST m=+1.024290401map[id:0]
2019/08/12 16:28:38 http
[pub] Message published:  1:2019-08-12 16:28:38.3884518 +0800 CST m=+2.024580201
2019/08/12 16:28:38 [sub] Received Body: %s,Header: %s
1:2019-08-12 16:28:38.3884518 +0800 CST m=+2.024580201map[id:1]
2019/08/12 16:28:39 http
[pub] Message published:  2:2019-08-12 16:28:39.3878092 +0800 CST m=+3.023937601
2019/08/12 16:28:39 [sub] Received Body: %s,Header: %s
2:2019-08-12 16:28:39.3878092 +0800 CST m=+3.023937601map[id:2]
2019/08/12 16:28:40 http
[pub] Message published:  3:2019-08-12 16:28:40.3881043 +0800 CST m=+4.024232701
2019/08/12 16:28:40 [sub] Received Body: %s,Header: %s
3:2019-08-12 16:28:40.3881043 +0800 CST m=+4.024232701map[id:3]
2019/08/12 16:28:41 http
[pub] Message published:  4:2019-08-12 16:28:41.3884312 +0800 CST m=+5.024559601
2019/08/12 16:28:41 [sub] Received Body: %s,Header: %s
4:2019-08-12 16:28:41.3884312 +0800 CST m=+5.024559601map[id:4]
2019/08/12 16:28:42 http
[pub] Message published:  5:2019-08-12 16:28:42.3887561 +0800 CST m=+6.024884501
2019/08/12 16:28:42 [sub] Received Body: %s,Header: %s
5:2019-08-12 16:28:42.3887561 +0800 CST m=+6.024884501map[id:5]
2019/08/12 16:28:43 http
[pub] Message published:  6:2019-08-12 16:28:43.3870869 +0800 CST m=+7.023215301
2019/08/12 16:28:43 [sub] Received Body: %s,Header: %s
6:2019-08-12 16:28:43.3870869 +0800 CST m=+7.023215301map[id:6]
2019/08/12 16:28:44 http
[pub] Message published:  7:2019-08-12 16:28:44.3885307 +0800 CST m=+8.024659101
2019/08/12 16:28:44 [sub] Received Body: %s,Header: %s
7:2019-08-12 16:28:44.3885307 +0800 CST m=+8.024659101map[id:7]
2019/08/12 16:28:45 http
[pub] Message published:  8:2019-08-12 16:28:45.3887328 +0800 CST m=+9.024861201
2019/08/12 16:28:45 [sub] Received Body: %s,Header: %s
8:2019-08-12 16:28:45.3887328 +0800 CST m=+9.024861201map[id:8]
2019/08/12 16:28:46 http
[pub] Message published:  9:2019-08-12 16:28:46.3870944 +0800 CST m=+10.023222801
2019/08/12 16:28:46 [sub] Received Body: %s,Header: %s
9:2019-08-12 16:28:46.3870944 +0800 CST m=+10.023222801map[id:9]
2019/08/12 16:28:47 http
[pub] Message published:  10:2019-08-12 16:28:47.3873887 +0800 CST m=+11.023517101
2019/08/12 16:28:47 [sub] Received Body: %s,Header: %s
10:2019-08-12 16:28:47.3873887 +0800 CST m=+11.023517101map[id:10]
2019/08/12 16:28:48 http
[pub] Message published:  11:2019-08-12 16:28:48.3887128 +0800 CST m=+12.024841201
2019/08/12 16:28:48 [sub] Received Body: %s,Header: %s
11:2019-08-12 16:28:48.3887128 +0800 CST m=+12.024841201map[id:11]
2019/08/12 16:28:49 http
[pub] Message published:  12:2019-08-12 16:28:49.3870651 +0800 CST m=+13.023193501
2019/08/12 16:28:49 [sub] Received Body: %s,Header: %s
12:2019-08-12 16:28:49.3870651 +0800 CST m=+13.023193501map[id:12]
2019/08/12 16:28:50 http
[pub] Message published:  13:2019-08-12 16:28:50.3873677 +0800 CST m=+14.023496101
2019/08/12 16:28:50 [sub] Received Body: %s,Header: %s
13:2019-08-12 16:28:50.3873677 +0800 CST m=+14.023496101map[id:13]
2019/08/12 16:28:51 http
[pub] Message published:  14:2019-08-12 16:28:51.3886879 +0800 CST m=+15.024816301
2019/08/12 16:28:51 [sub] Received Body: %s,Header: %s
14:2019-08-12 16:28:51.3886879 +0800 CST m=+15.024816301map[id:14]
2019/08/12 16:28:52 http
[pub] Message published:  15:2019-08-12 16:28:52.3870503 +0800 CST m=+16.023178701
2019/08/12 16:28:52 [sub] Received Body: %s,Header: %s
15:2019-08-12 16:28:52.3870503 +0800 CST m=+16.023178701map[id:15]
2019/08/12 16:28:53 http
[pub] Message published:  16:2019-08-12 16:28:53.3875243 +0800 CST m=+17.023652701
2019/08/12 16:28:53 [sub] Received Body: %s,Header: %s
16:2019-08-12 16:28:53.3875243 +0800 CST m=+17.023652701map[id:16]
2019/08/12 16:28:54 http
[pub] Message published:  17:2019-08-12 16:28:54.3885713 +0800 CST m=+18.024699701
2019/08/12 16:28:54 [sub] Received Body: %s,Header: %s
17:2019-08-12 16:28:54.3885713 +0800 CST m=+18.024699701map[id:17]
2019/08/12 16:28:55 http
[pub] Message published:  18:2019-08-12 16:28:55.3872265 +0800 CST m=+19.023354901
2019/08/12 16:28:55 [sub] Received Body: %s,Header: %s
18:2019-08-12 16:28:55.3872265 +0800 CST m=+19.023354901map[id:18]

END

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原文发布于微信公众号 - 陌无崖(gh_ebbdb61f463e)

原文发表时间:2019-08-12

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