蟒蛇MQTT腳本來發送和接收消息

Question

MQTT問題：

嗨，我試圖建立多樹莓派之間的MQTT網絡（從2開始）。 我有一個覆蓋有熱敏電阻傳感器的樹莓派（RPi-A）MQTT客戶端，以及一個作爲我的網絡集線器的覆盆子（RPi-B）MQTT經紀人/客戶端。 通過python腳本，我想每隔30分鐘從RPi-A通過MQTT發送溫度到主題傳感器/數據並由RPi-B接收。 當RPi-B通過主題傳感器/數據接收到來自RPi-A的消息時，我希望它通過MQTT主題傳感器/指令向RPi-A發送指令。 以下是我的腳本，到目前爲止RPi-A可以發送消息，RPi-B可以接收它們，但是我無法弄清楚RPi-B如何響應。

基本上，我想了解的是，MQTT設備可能同時充當代理和客戶端嗎？ 而且，客戶端是否可以發送和接收消息，如果有的話如何通過python實現以上所有內容？ 我讀過很多博客，官方MQTT文章和paho模塊文檔（對我來說這很難理解），但仍然無法弄清楚。你的幫助將是最有用的/讚賞的。

代碼RPI-A（與熱敏電阻傳感器）：

from sense_hat import SenseHat 
import time 
import paho.mqtt.client as mqtt 
import paho.mqtt.publish as publish 
sense = SenseHat() 

Broker = "192.168.1.252" 

sub_topic = "sensor/instructions" # receive messages on this topic 

pub_topic = "sensor/data"  # send messages to this topic 


############### sensehat inputs ################## 

def read_temp(): 
    t = sense.get_temperature() 
    t = round(t) 
    return t 

def read_humidity(): 
    h = sense.get_humidity() 
    h = round(h) 
    return h 

def read_pressure(): 
    p = sense.get_pressure() 
    p = round(p) 
    return p 

def display_sensehat(message): 
    sense.show_message(message) 
    time.sleep(10) 

############### MQTT section ################## 

# when connecting to mqtt do this; 

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

# when receiving a mqtt message do this; 

def on_message(client, userdata, msg): 
    message = str(msg.payload) 
    print(msg.topic+" "+message) 
    display_sensehat(message) 

def publish_mqtt(sensor_data): 
    mqttc = mqtt.Client("python_pub") 
    mqttc.connect(Broker, 1883) 
    mqttc.publish(pub_topic, sensor_data) 
    #mqttc.loop(2) //timeout = 2s 

def on_publish(mosq, obj, mid): 
    print("mid: " + str(mid)) 


client = mqtt.Client() 
client.on_connect = on_connect 
client.on_message = on_message 
client.connect(Broker, 1883, 60) 


while True: 
    sensor_data = [read_temp(), read_humidity(), read_pressure()] 
    publish.single("monto/solar/sensors", str(sensor_data), hostname = Broker) 
    time.sleep(1*60) 

代碼RPI-B（網絡集線器）：

import time 
import paho.mqtt.client as mqtt 
import paho.mqtt.publish as publish 

Broker = "192.168.1.252" 

sub_topic = "sensor/data" # receive messages on this topic 

pub_topic = "sensor/instructions"    # send messages to this topic 


# mqtt section 

# when connecting to mqtt do this; 

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

# when receiving a mqtt message do this; 

def on_message(client, userdata, msg): 
    message = str(msg.payload) 
    print(msg.topic+" "+message) 
    publish_mqtt(‘got your message’) 

# to send a message 

def publish_mqtt(sensor_data): 
    mqttc = mqtt.Client("monto_hub") 
    mqttc.connect(Broker, 1883) 
    mqttc.publish(pub_topic, "this is the master speaking") 
    #mqttc.loop(2) //timeout = 2s 

def on_publish(mosq, obj, mid): 
    print("mid: " + str(mid)) 


client = mqtt.Client() 
client.on_connect = on_connect 
client.on_message = on_message 
client.connect(Broker, 1883, 60) 
client.loop_forever() 

Answer 1

最簡單的方法是開始於一個單獨的線程在網絡環使用client.loop_start()功能，然後用正常client.publish方法

from sense_hat import SenseHat 
import time 
import paho.mqtt.client as mqtt 
import paho.mqtt.publish as publish 
sense = SenseHat() 

Broker = "192.168.1.252" 

sub_topic = "sensor/instructions" # receive messages on this topic 

pub_topic = "sensor/data"  # send messages to this topic 


############### sensehat inputs ################## 

def read_temp(): 
    t = sense.get_temperature() 
    t = round(t) 
    return t 

def read_humidity(): 
    h = sense.get_humidity() 
    h = round(h) 
    return h 

def read_pressure(): 
    p = sense.get_pressure() 
    p = round(p) 
    return p 

def display_sensehat(message): 
    sense.show_message(message) 
    time.sleep(10) 

############### MQTT section ################## 

# when connecting to mqtt do this; 

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

# when receiving a mqtt message do this; 

def on_message(client, userdata, msg): 
    message = str(msg.payload) 
    print(msg.topic+" "+message) 
    display_sensehat(message) 

def on_publish(mosq, obj, mid): 
    print("mid: " + str(mid)) 


client = mqtt.Client() 
client.on_connect = on_connect 
client.on_message = on_message 
client.connect(Broker, 1883, 60) 
client.loop_start() 

while True: 
    sensor_data = [read_temp(), read_humidity(), read_pressure()] 
    client.publish("monto/solar/sensors", str(sensor_data)) 
    time.sleep(1*60)