Question

我使用mqtt协议将传感器数据的消息发送到mosquitto代理。我想做的是每隔t秒发送一次传感器数据，但是如果我收到一条消息并行处理它。我很想使用时间。睡觉（），但我认为这会延迟＆＃34; on_message＆＃34;功能也。使用paho-mqtt和python 2.7。关于如何完成这样的事情的任何想法？

客户编号1。（发送传感器数据）

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

def on_connect(client, userdata, rc):
    mqttc.subscribe(topic='/+/mysignals/status', qos=0)
    mqttc.subscribe(topic='/+/mysignals/add_sensor',qos=0)
    mqttc.subscribe(topic='/+/mysignals/remove_sensor',qos=0)

def on_message(client,userdata,message):
    print 'received data'
    base_topic = '/mysignals'
    member_id = message.topic.split('/')[1]
    status_topic = '/mysignals/status'
    add_sensor_topic = '/mysignals/add_sensor'
    remove_sensor_topic = '/mysignals/remove_sensor'
    log_topic = '/log'
    if status_topic in message.topic:
        action = mysignals_test.change_status(int(member_id),int(message.payload))
        mqttc.publish(topic='/'+member_id+status_topic+log_topic+'/',payload=action,qos=0)
    elif add_sensor_topic in message.topic:
        action = mysignals_test.add_sensor(message.playload,int(member_id))
        mqttc.publish(topic='/'+member_id+add_sensor_topic+log_topic+'/',payload=action,qos=0)
    elif remove_sensor_topic in message.topic:
        action = mysignals_test.remove_sensor(message.payload,int(member_id))
        mqttc.publish(topic='/'+member_id+remove_sensor_topic+log_topic+'/',payload=action,qos=0)
    else:
        mqttc.publish(topic='/'+member_id+base_topic+log_topic+'/',payload='Wrong Action.',qos=0)

mysignals_test = mysignals(email='blablabla',password='blabla')
mysignals_test.add_sensor('temp',150)
mysignals_test.change_status(150,1)
mqttc = mqtt.Client(client_id='mysignals')
mqttc.on_connect = on_connect
mqttc.on_message = on_message
mqttc.connect('broker ip')
mqttc.loop_start()

while True:
    for member in mysignals_test.members:
        if member.status == 1:
            live_data = mysignals_test.live(member.member_id)
            for data in live_data:
                topic = '/'+str(data.member_id)+'/mysignals/'+str(data.sensor_id)+'/'
                qos = 0
                retain = False
                if 'raw' in data.sensor_id:
                    payload = data.values
                else:
                    payload = data.value
                mqttc.publish(topic=topic,payload=payload,qos=qos,retain=retain)
    print 'sent data'
    time.sleep(55)

客户端No2（从客户端接收数据1.仅限订户。也向client1.only订阅者发送测试消息。）

import paho.mqtt.client as mqtt

def on_connect(client, userdata, rc):
    mqttc.subscribe(topic='/+/mysignals/+/', qos=0)
    mqttc.subscribe(topic='/+/mysignals/status/+/', qos=0)
def on_disconnect(client,userdata,rc):
    pass
def on_message(client, userdata, message):
    if str(message.payload) == '':
        print 'empty message'
    else:
        print 'Received message :' + str(message.payload) + ', on topic: '+ message.topic + ', with QoS: ' + str(message.qos) 
        mqttc.publish(topic='/154/mysignals/status',payload=0,qos=0)

mqttc = mqtt.Client(client_id='P1')
mqttc.on_connect = on_connect
mqttc.on_disconnect = on_disconnect
mqttc.on_message = on_message
mqttc.connect('broker ip')
mqttc.loop_start()

仅供记录＆＃34; mysignals＆＃34;对象是由我制作的，它不存在于那里。上面的代码的问题是，当客户端2接收到传感器数据时，它会挂起并将测试消息无条件地发送回代理。客户端2发送时的测试消息接收传感器数据应该由客户端1读取，客户端1应该操纵＆＃34; mysignals＆＃34;相应的对象。

客户2输出：

Received message :25.4, on topic: /150/mysignals/temp/, with QoS: 0
Received message :Success, on topic: /154/mysignals/status/log/, with QoS: 0
Received message :Success, on topic: /154/mysignals/status/log/, with QoS: 0
Received message :Success, on topic: /154/mysignals/status/log/, with QoS: 0
Received message :Success, on topic: /154/mysignals/status/log/, with QoS: 0
Received message :Success, on topic: /154/mysignals/status/log/, with QoS: 0
Received message :Success, on topic: /154/mysignals/status/log/, with QoS: 0
Received message :Success, on topic: /154/mysignals/status/log/, with QoS: 0
Received message :Success, on topic: /154/mysignals/status/log/, with QoS: 0
Received message :Success, on topic: /154/mysignals/status/log/, with QoS: 0
Received message :Success, on topic: /154/mysignals/status/log/, with QoS: 0
Received message :Success, on topic: /154/mysignals/status/log/, with QoS: 0
Received message :Success, on topic: /154/mysignals/status/log/, with QoS: 0
Received message :Success, on topic: /154/mysignals/status/log/, with

客户1输出：

Login Successfull.
sent data
sent data
received data
received data
received data
received data
received data
received data
received data
received data

PS：我不包括＆＃34; mysignals.py＆＃34;因为大约有200行。

Answer 1

我对Paho MQTT库中回调函数的运行方式的理解是后台循环（由loop_start启动）将中断主线程，所以我不担心使用time.sleep（）的延迟。因此，如果您主要关注的是不延迟on_message回调，那么它应该不是问题。我经常在使用MQTT回调的Python脚本中使用sleep。

当然回调可能会稍微延迟传感器发送数据，但实际上您是否需要以绝对精确的时序发送数据？大多数数据库（例如RRD）可以轻松适应略微关闭的更新时间。或者，如果您的on_message回调花费了不可接受的长时间来处理，请考虑将MQTT消息的有效负载传递出回调函数，并在脚本的其他位置处理它。

如果您确实需要传感器更新的瞬间精度，请考虑将功能分成两个脚本（或线程），每个脚本只用于一个目的（发送或接收）。

Answer 2

好的，我设法得到了预期的结果。我必须在状态子主题上创建2个子主题。一个客户端应该写在状态suptopic的日志子主题上，一个客户端应该在状态子主题的值子主题上写.Also我删除了订阅上的qos参数。我还添加了time.sleep（），我很少会错过一条消息。只有在非常短的时间间隔内收到2条消息。最大的问题是我没有理解主题和子主题是如何实际的工作。

在等待消息时发送消息

2 个答案: