重新连接后订阅者收不到消息

Question

N.B。我使用 EMQX 作为代理，使用 python-paho 作为客户端库。我不确定是哪个问题造成的。

如果发布者在一段时间内没有发送任何消息，订阅者会断开连接，但也会重新连接（因为 loop_forever 会自动处理重新连接）。但是重连后，如果生产者再次开始发送数据，自动重连的服务器是收不到消息的。那样的话，订阅者需要重新开始（手动重连）

我的订阅者

import paho.mqtt.client as mqttClient
import json
import datetime

def on_connect(client, userdata, flags, rc):

    if rc == 0:
        print("Connected to broker")

    else:
        print("Connection failed")

def on_disconnect(client, userdata, rc):
    if rc != 0:
        print("Unexpected MQTT disconnection. Will auto-reconnect")
    

def on_message(client, userdata, message):
    print(str(datetime.datetime.now())+str(message.payload) + "\n")


#broker_address= "3.121.233.176" 
broker_address= "address_of_the_broker" 
port = 1883                     
client = mqttClient.Client("clientLB1")               #create new instance
client.on_connect= on_connect                      #attach function to callback
client.on_message= on_message                      #attach function to callback
client.on_disconnect = on_disconnect
client.connect(broker_address,port,60)
client.subscribe("xdk1") #subscribe
client.loop_forever() #then keep listening forever

我的发布者：

import paho.mqtt.client as paho
import time
from random import random

def on_publish(client, userdata, mid):
    print("mid: "+str(mid))
 
client = paho.Client()
client.on_publish = on_publish
#client.connect("35.157.39.224", 1883)
client.connect("LBmqtt-1826452731.eu-central-1.elb.amazonaws.com", 1883)
client.loop_start()

while True:
    temperature = random()
    (rc, mid) = client.publish("xdk1", str(temperature), qos=1)
    time.sleep(.1)

如何解决这个问题？

Answer 1

通过

解决了

client = mqttClient.Client("client_name",clean_session=False)

来自文档：

clean_session: a boolean that determines the client type. If True, the broker will remove all information about this client when it disconnects. If False, the client is a durable client and subscription information and queued messages will be retained when the client disconnects.

重新连接后订阅者收不到消息

after reconnection subscriber does not getting messages

python

mqtt

paho

emq