用MQTT和Python控制程序

伙计们。因此，我对Python比较陌生，是MQTT的新手。因此，我试图通过MQTT实现两个程序的简单连接。其中一个程序是发布者：

   import paho.mqtt.client as mqtt
   import sys, tty, termios 
   ## Publisher reads a keyboard input 
   def getch():
       fd = sys.stdin.fileno()
       old_settings = termios.tcgetattr(fd)
       try:
           tty.setraw(sys.stdin.fileno())
           ch = sys.stdin.read(1)
       finally:
           termios.tcsetattr(fd,termios.TCSADRAIN, old_settings)
           return ch

   while True:
   ##Publisher connects to MQTT broker
       mqttc= mqtt.Client("python_pub")
       mqttc.connect("iot.eclipse.org", 1883)
       char= getch()
       mqttc.publish("Labbo/control", str(char))
       mqtt.Client()

因此，发布者基本上读取密钥输入并将其发送给代理。 客户端程序应该读取按键笔划并做出相应反应：

   import paho.mqtt.client as mqtt

   def on_connect(client, userdata, flags, rc):
       print("Connected with result code "+str(rc))
       client.subscribe("Labbo/control")

   def on_message(client, userdata, msg):
       print(msg.topic+" "+str(msg.payload))
   ## v v PROBLEM LINE v v ## 
   char=str(msg.payload)
   ## ^ ^ PROBLEM LINE ^ ^ ##
   client = mqtt.Client()
   client.on_connect = on_connect
   client.on_message = on_message  
   client.connect("iot.eclipse.org", 1883, 60)
   ##The program just needs to close itself upon entering "x" on the Publisher
   while True:
       if char=="x":
          break

---

这是一个简单的测试程序，但我在尝试“读取”MQTT有效负载时遇到了很多麻烦。

您的订户代码正在循环，没有做任何有成效的事情。必须按如下方式进行更改

import paho.mqtt.client as mqtt

def on_connect(client, userdata, flags, rc):
   print("Connected with result code "+str(rc))
   client.subscribe("Labbo/control")

def on_message(client, userdata, msg):
   print(msg.topic+" "+str(msg.payload))
   char = str(msg.payload)
   if char == 'x':
       client.disconnect()

client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message
client.connect("iot.eclipse.org", 1883, 60)
client.loop_forever()

您的发布者代码也是如此，它在其中创建了一个新的客户端来发送一封信，这有点过分了

import paho.mqtt.client as mqtt
import sys, tty, termios
## Publisher reads a keyboard input 
def getch():
    fd = sys.stdin.fileno()
    old_settings = termios.tcgetattr(fd)
    try:
        tty.setraw(sys.stdin.fileno())
        ch = sys.stdin.read(1)
    finally:
        termios.tcsetattr(fd,termios.TCSADRAIN, old_settings)
    return ch


##Publisher connects to MQTT broker
mqttc= mqtt.Client("python_pub")
mqttc.connect("iot.eclipse.org", 1883)
mqttc.loop_start()

while True:
    char= getch()
    mqttc.publish("Labbo/control", str(char))

---

发布者代码还应在进入while True:loop之前调用mqttc.start\u loop（），以确保发送保持活动状态的消息，并且可以处理大型发布（在这种情况下实际上不需要，但形式良好）