MQTT入门 - 公开的服务Broker

带带大师兄 2021-05-17 17:34:42

使用MQTT，前提是需要一个服务器Server/Broker，除了自己搭建服务，刚开始时可以使用第三方提供的在线公开的免费Broker服务。使用这些免费Broker服务，可以在刚开始时快速理解MQTT协议。

其他：https://github.com/mqtt/mqtt.github.io/wiki/public_brokers

这些Broker/Server已经搭建好了，只需要编写Client/Subscriber就能测试一下MQTT了。

以使用Python的paho-mqtt来实现客户端。连接test.mosquitto.org服务为例。

（1）安装Eclipse Paho客户端

Shell代码

pip install paho-mqtt

（2）客户端连接

unencrypted-mqtt.py

Python代码

# coding=utf8  
import paho.mqtt.client as mqtt  
  
def on_connect(client, userdata, flags, rc):  
    print("Connected with result code "+str(rc))  
    client.subscribe("test/rensanning/time")  
  
def on_message(client, userdata, msg):  
    print(msg.topic+" "+str(msg.payload))  
  
client = mqtt.Client()  
client.on_connect = on_connect  
client.on_message = on_message  
  
client.connect("test.mosquitto.org", 1883)  
client.loop_forever()

执行 python unencrypted-mqtt.py

（2）发布消息

pub-mqtt.py

Python代码

# coding=utf8  
import paho.mqtt.client as mqtt  
import time  
  
def on_connect(client, userdata, flags, rc):  
    print("Connected with result code "+str(rc))  
  
def on_message(client, userdata, msg):  
    print(msg.topic+" "+str(msg.payload))  
  
client = mqtt.Client()  
client.on_connect = on_connect  
client.on_message = on_message  
client.connect("test.mosquitto.org", 1883)  
  
while client.loop() == 0:  
    msg = "test message from Publisher "+time.ctime()  
    client.publish("test/rensanning/time", msg, 0, True)  
    print("message published")  
    time.sleep(1.5)  
    pass

执行 python pub-mqtt.py

（3）订阅消息

sub-mqtt.py

Python代码

# coding=utf8  
import paho.mqtt.client as mqtt  
  
def on_connect(client, userdata, flags, rc):  
    print("Connected with result code "+str(rc))  
    client.subscribe("test/rensanning/time")  
  
def on_message(client, userdata, msg):  
    print(msg.topic+" "+str(msg.payload))  
  
client = mqtt.Client()  
client.on_connect = on_connect  
client.on_message = on_message  
  
client.connect("test.mosquitto.org", 1883)  
client.loop_forever()

执行 python sub-mqtt.py

同时运行订阅和发布客户端。

加密通信，访问8883端口

先从 http://test.mosquitto.org/ 下载 mosquitto.org.crt文件。

pub-mqtt-tls.py

Python代码

# coding=utf8  
import paho.mqtt.client as mqtt  
import time  
  
def on_connect(client, userdata, flags, rc):  
    print("Connected with result code "+str(rc))  
  
def on_message(client, userdata, msg):  
    print(msg.topic+" "+str(msg.payload))  
  
client = mqtt.Client()  
client.on_connect = on_connect  
client.on_message = on_message  
client.tls_set("mosquitto.org.crt")  
client.connect("test.mosquitto.org", 8883)  
  
while client.loop() == 0:  
    msg = "test message from Publisher "+time.ctime()  
    client.publish("test/rensanning/time", msg, 0, True)  
    print("message published")  
    time.sleep(1.5)  
    pass

执行 python pub-mqtt-tls.py