Question

我使用Mosquitto（现在的Paho）python MQTT客户端连接到HiveMQ代理。代码非常基础，取自他们的文档 - https://pypi.python.org/pypi/paho-mqtt

#SUBSCRIBER
import paho.mqtt.client as mqtt

# The callback for when the client receives a CONNACK response from the server.
def on_connect(client, userdata, rc):
    client.subscribe("GB/node0/", 2) 

# The callback for when a PUBLISH message is received from the server.
def on_message(client, userdata, msg):
    print "Topic: ", msg.topic+'\nMessage: '+str(msg.payload)

client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message

client.connect("192.168.15.4", 1883, 60)

# Blocking call that processes network traffic, dispatches callbacks and
# handles reconnecting.
client.loop_forever()

正如您在client.subscribe（）中注意到的那样，QoS是2.这是对官方文档代码的唯一修改。

发布客户的代码是 -

#PUBLISHER
import paho.mqtt.client as mqtt    
mqttc = mqtt.Client("python_pub")
mqttc.connect("192.168.15.4", 1883, 60)   
mqttc.publish("GB/node0/", "Hello, World baby!",2)

此处，QoS也是2.

QoS的这种修改导致订户仅接收20条消息。在进一步探测之后，我意识到问题可能是由max_inflight_messages_set()引起的，{{1}}是一个选项函数，它设置QoS> 0的最大消息数，这些消息可以同时通过其网络流。默认值为20.

但是，将其更改为任何其他值都不起作用。此外，为什么客户认为这些消息在收到后仍然存在？我该如何解决这个问题？我如何确保客户理解这些消息不是＆＃34; inflight＆＃34;并已交付？

Answer 1

尝试在发布商mqttc.loop(2,10)之后调用mqttc.publish()，以便发布商可以处理来自代理的已收到发布的QOS2确认。

2秒超时和10个数据包可能超过需要但它应该工作

Answer 2

@hardillb是对的，你需要某种形式的loop*()电话。更确切地说，这样做：

import paho.mqtt.client as mqtt

def on_publish(client, userdata, mid):
    client.disconnect()

mqttc = mqtt.Client() # There's normally no need to set a client id.
mqttc.on_publish = on_publish
mqttc.connect("192.168.15.4", 1883, 60)
mqttc.publish("GB/node0/", "Hello, World baby!",2)
mqttc.loop_forever()

或者：

import paho.mqtt.publish as paho
paho.single("GB/node0/", "Hello, World baby!", qos=2, hostname="192.168.15.4")

使用Mosquitto / Paho for Python无法接收超过20条MQTT消息

2 个答案: