Develop Reference

Why don't wildcard topics (#, +) work in Python paho MQTT Subscribe with retained messages?

I use paho.mqtt. And I send messange to topic test/data/user1
My Subscribe Client:
from paho.mqtt import client as mqtt_client
host = 'myhost.com'
port = 1883
topic = 'test/data/#'
auth = {
'username': 'myuser',
'password': 'mypass'
}
client_id = 'python-mqtt-1'
def connect_mqtt() -> mqtt_client:
def on_connect(client, userdata, flags, rc):
if rc == 0:
print("Connected to MQTT Broker!")
else:
print("Failed to connect, return code %d\n", rc)
client = mqtt_client.Client(client_id)
client.username_pw_set(**auth)
client.on_connect = on_connect
client.connect(host, port)
return client
def subscribe(client: mqtt_client):
def on_message(client, userdata, msg):
print(f"Received `{msg.payload.decode()}` from `{msg.topic}` topic")
client.subscribe(topic)
client.on_message = on_message
def run():
client = connect_mqtt()
subscribe(client)
client.loop_forever()
if __name__ == '__main__':
run()
But I don't get my messange with topic='test/data/#'. If I use topic='test/data/user1', I get my messange. Why is the wildcard theme not working?
My broker is RabbitMQ.

So apparently RabbitMQ itself doesn't support this feature.
https://github.com/rabbitmq/rabbitmq-server/issues/2556

How to publish with many publishers to one subscriber?

I need to build a network with multiple publishers, one broker, and one subscriber.
Issue:
I have a working code with one to one option (one pub - one sub). However, when I run more publishers the subscriber receives messages only from the last connected publisher and I have no idea why it is happening.
More information: Broker (mosquitto) is working in a docker container, each publisher is a separate script and the target is to run multiple docker containers with one publisher in each container, but now I need to work around the communication issue.
Does anyone have any clues or ideas on how to debug or solved this?
This is the publisher script:
import time
import paho.mqtt.client as mqtt
import datetime
import random
import json
import logging
from multiprocessing import Process
CLEAN_SESSION = False
def on_connect(client, userdata, flags, rc):
logging.info(f"New connection {client}, {rc}")
def sensor(client_id):
localhost = '172.17.0.2'
port = 1883
timeout = 60
topic = "/mia/sensor"
client_id = f"sensor_{client_id}"
def check_sensor():
time.sleep(1)
rand = random.randint(0, 10)
if rand > 5:
current_time = datetime.datetime.now()
current_time = current_time.strftime('%Y-%m-%d %H:%M:%S')
return {"time": current_time, "signal": 1, "id": client_id}
else:
return 0
client = mqtt.Client(client_id, clean_session=CLEAN_SESSION)
client.on_connect = on_connect
client.connect(localhost, port, timeout)
while True:
check_info = check_sensor()
if check_info:
message_payload = json.dumps(check_info)
logging.info(message_payload)
client.publish(topic, message_payload, qos=2)
client.loop()
client.disconnect()
if __name__ == "__main__":
p = Process(target=sensor, args=(1,))
p.start()
print("new publisher created!")
This is the subscriber script:
import paho.mqtt.client as mqtt
import paho.mqtt.subscribe as sub
import json
import logging
localhost = '172.17.0.2'
port = 1883
timeout = 60
topic = "/mia/sensor"
def on_connect(client, userdata, flags, rc):
logging.info(f"New connection {client}, {rc}")
client.subscribe(topic, qos=2)
def on_message(client, userdata, msg):
data = json.loads(msg.payload.decode('utf-8'))
logging.debug(f"new message from {client} - {data}")
print(data)
client = mqtt.Client("python", clean_session=False)
client.on_connect = on_connect
client.on_message = on_message
client.connect_async(localhost, port, timeout)
client.loop_forever()
Thanks in advance

Your client_id needs to be unique. Check that.

How to set up proxy in your script and publish a topic using mqtt-paho in python?

The below code will run perfectly in my home network but when i am using my office network it wont, throwing some error. So i thought to use proxy in my script, again after that getting some proxy related error .
import paho.mqtt.client as paho
import time
import socket
import socks
broker = 'iot.eclipse.org'
def on_connect(client, userdata, flags, rc):
if rc == 0:
print('Connected OK')
else:
print('Bad Connection returned code=', rc)
# print("CONNACK received with code %d." % (rc))
def on_log(client, userdata, level, buf):
print('log :' + buf)
def on_disconnect(client, userdata, flags, rc=0):
print('Disconnected result code ', str(rc))
def on_message(client, userdata, msg):
print('topic: '+msg.topic, 'payload: '+str(msg.payload))
client = paho.Client('python2')
client.on_connect = on_connect
client.on_disconnect = on_disconnect
client.on_message = on_message
client.on_log = on_log
socks.set_default_proxy(socks.SOCKS5, 'proxyhost.com', 1180)
socket.socket = socks.socksocket
print('Connecting to broker', broker)
client.connect(broker, 1883, 60)
client.loop_start()
client.subscribe('test/iotglab')
client.publish('test/iotglab', 'Hello Client')
time.sleep(4)
client.loop_stop()
client.disconnect()
I got proxy which is look like socks5h://hostname.com.

Subscribe and read several topics on mqtt mosquitto using python paho

I managed to publish on several topics and read one of them. What I need to do is to listen and read to all published topics and get messages. This is the code I use:
Publish messages to 3 topics :
#!/usr/bin/env python3
import paho.mqtt.client as mqtt
client = mqtt.Client()
client.connect("localhost",1883,60)
client.publish("topic/1", "400 | 350 | 320 | 410");
client.publish("topic/2", "200 | 350 | 420 | 110");
client.publish("topic/3", "200 | 350 | 420 | 110");
client.disconnect();
Subscribe and read messages for 1 topic
#!/usr/bin/env python3
import paho.mqtt.client as mqttClient
import time
def on_connect(client, userdata, flags, rc):
if rc == 0:
print("Connected to broker")
global Connected #Use global variable
Connected = True #Signal connection
else:
print("Connection failed")
def on_message(client, userdata, message):
print "Message received : " + message.payload
Connected = False
broker_address= "localhost"
port = 1883
client = mqttClient.Client("Python")
client.on_connect= on_connect
client.on_message= on_message
client.connect(broker_address, port=port)
client.loop_start()
while Connected != True:
time.sleep(0.1)
client.subscribe("topic/2")
try:
while True:
time.sleep(1)
except KeyboardInterrupt:
print "exiting"
client.disconnect()
client.loop_stop()

You can call the client.subscribe() function multiple times to subscribe to multiple topics.
Also you should move the calls to subscribe to the on_connect callback to remove the need for the first loop.
#!/usr/bin/env python3
import paho.mqtt.client as mqttClient
import time
def on_connect(client, userdata, flags, rc):
if rc == 0:
print("Connected to broker")
client.subscribe("topic/1")
client.subscribe("topic/2")
client.subscribe("topic/3")
client.subscribe("topic/4")
else:
print("Connection failed")
def on_message(client, userdata, message):
print("Message received : " + str(message.payload) + " on " + message.topic)
broker_address= "localhost"
port = 1883
client = mqttClient.Client("Python")
client.on_connect= on_connect
client.on_message= on_message
client.connect(broker_address, port=port)
client.loop_start()
try:
while True:
time.sleep(1)
except KeyboardInterrupt:
print("exiting")
client.disconnect()
client.loop_stop()
EDIT:
You can also subscribe to multiple topics in one go with the following syntax
client.subscribe([("topic/1", 0), ("topic/2", 0), ("topic/3", 0),("topic/4", 0)])

MQTT: How to send a message without to call loop_forever()

I'm using MQTT since a while to monitor some channels I subscribed. Now I want to implement to send a message as reaction to a state. I got it running with the code below, where I just react in the on_message callback (code 1 at the end). But this code uses
loop_forever()
in the main code which is blocking.
What I would like to do is to just send a single message to MQTT. When I try the following (with all different loop-functions), nothing is received by the MQTT server:
import paho.mqtt.client as mqtt
if __name__ == "__main__":
mqtt_client = mqtt.Client()
mqtt_client.connect("192.168.178.204", 1883, 60)
mqtt_client.username_pw_set(username="test", password="test")
mqtt_client.publish(topic='TEST', payload='CCCCCCCCC', retain=False)
mqtt_client.loop_write()
# mqtt_client.loop()
# mqtt_client.loop_start()
mqtt_client.disconnect()
How can I send a message to MQTT which does not block the process?
Code 1:
import paho.mqtt.client as mqtt
def on_connect(client, userdata, rc):
topic_list = [("TEST_MS", 1)]
if rc == 0:
print("Successful connected and subscribed to: {}".format(topic_list))
client.subscribe(topic_list)
def on_message(client, userdata, msg):
print(msg.payload)
client.publish(topic='TEST_MS2', payload=msg.payload, retain=False)
def on_publish(client, userdata, mid):
print("message published")
def on_subscribe(mosq, obj, mid, granted_qos):
print("Subscribed: " + str(mid) + " " + str(granted_qos))
if __name__ == "__main__":
mqtt_client = mqtt.Client()
mqtt_client.on_connect = on_connect
mqtt_client.on_message = on_message
mqtt_client.on_publish = on_publish
mqtt_client.on_subscribe = on_subscribe
mqtt_client.connect("192.168.178.204", 1883, 60)
mqtt_client.username_pw_set(username="test", password="test")
# mqtt_client.publish(topic='TEST_MS', payload='CCCCCCCCC', retain=False)
mqtt_client.loop_forever()
mqtt_client.disconnect()

If you want to send just a single message and then exit use the API specifically for that. Docs here
import paho.mqtt.publish as publish
publish.single("paho/test/single", "payload", hostname="iot.eclipse.org")