Situation:
I have a python virtual sensor (a python program) that submits data via MQTT protocol to my device in ThingsBoard.
I can visualize data on the dashboard, so I'm sure that the data are received.
Problem:
When I try to connect a python subscriber to the thingsboard broker (demo.thingsboard.io) using paho I obtain that the connection code is 0, so the connection is OK, however I see that the dashboard stops visualising the data from the virtual sensor but the subscriber does not receive anything.
The virtual sensor is publishing at v1/devices/me/telemetry and the subscriber is subscribed at the same topic v1/devices/me/telemetry.
How to show the data published by the virtual sensor on my subscriber client?
VIRTUAL SENSOR CODE:
import paho.mqtt.client as paho #mqtt library
import os
import json
import time
from datetime import datetime
ACCESS_TOKEN="vgFztmvT6bps7JCeOEZq" #Token of your device
broker="demo.thingsboard.io" #host name
port=1883 #data listening port
def on_publish(client,userdata,result): #create function for callback
print("data published to thingsboard \n")
pass
client1= paho.Client("control1") #create client object
client1.on_publish = on_publish #assign function to callback
client1.username_pw_set(ACCESS_TOKEN) #access token from thingsboard device
client1.connect(broker,port,keepalive=60) #establish connection
while True:
payload="{"
payload+="\"Humidity\":60,";
payload+="\"Temperature\":25";
payload+="}"
ret= client1.publish("v1/devices/me/telemetry",payload) #topic-v1/devices/me/telemetry
print("Please check LATEST TELEMETRY field of your device")
print(payload);
time.sleep(5)
CLIENT SUBSCRIBER CODE:
import paho.mqtt.client as mqtt
import time
token = "vgFztmvT6bps7JCeOEZq"
broker="demo.thingsboard.io" # host name
port=1883
topic = "v1/devices/me/telemetry"
# The callback for when the client receives a CONNACK response from the server.
def on_connect(client, userdata, flags, rc) :
if (rc==0) :
print("connected OK Returned code = ", rc)
else :
print("Bad connection Returned code = ", rc)
def on_message(client, userdata, msg) :
print (msg.topic + " " + str(msg.payload))
client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message
client.username_pw_set(token)
client.connect(broker , port, 60)
client.subscribe(topic)
client.loop_forever()
In you publisher client , you are using a topic named:"v1/devices/me/telemetry".
However, you are not subscribing to the same topic using the subscriber client.
Change the following line in your Subscriber client program:
client.subscribe(token)
to
client.subscribe(topic)
This should solve the problem.
I believe TB will only allow for one connection per client so you should use different access_keys for your publisher and subscriber.
Try to use tcp://51.159.155.114 but not demo.thingsboard.io
Related
I am having an issue with the code below.
The code works perfectly at the beginning. First it says Connected to MQTT Broker! and receives data from it. But after a long time (like 6 hours, or 10 hours etc.) it says again Connected to MQTT Broker! and after that id does not receive any other data.
I am trying to make this program work forever, but i don't know what i have done wrong.
Any ideas?
# python3.6
import random
import mysql.connector
from paho.mqtt import client as mqtt_client
import json
# Code for MQTT Connection
broker = 'YOUR_BROKER'
port = 1883
topic = "YOUR_TOPIC"
# generate client ID with pub prefix randomly
client_id = f'python-mqtt-{random.randint(0, 100)}'
username = "THE_USERNAME"
password = "THE_PASSWORD"
# Function to connect on mqtt
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(username, password)
client.on_connect = on_connect
client.connect(broker, port)
return client
# function to subscribe from mqtt
def subscribeFunc(client: mqtt_client):
def on_messageFunc(client, userdata, msg):
print(f"Received `{msg.payload.decode()}` from `{msg.topic}` topic")
client.subscribe(topic)
client.on_message = on_messageFunc
def run():
client = connect_mqtt()
subscribeFunc(client)
client.loop_forever()
if __name__ == '__main__':
run()
I tried to find the problem but it seems that nothing changed significantly.
I am expecting this program to receive data without stopping.
Network connections may not be 100% reliable (and servers etc are restarted from time to time) so expecting the connection to remain up forever is unrealistic. The issue with your code is that it connects then subscribes; if the connection is dropped it does not resubscribe. As the connection is clean_session=true and subscription qos=0 (the defaults) the broker will forget about any active subscriptions when the connection drops (so the client will reconnect but not receive any more messages).
The Simple solution is to use the approach shown in the docs and subscribe in the on_connect callback (that way the subscription will be renewed after reconnection):
def on_connect(client, userdata, flags, rc):
# Subscribing in on_connect() means that if we lose the connection and
# reconnect then subscriptions will be renewed.
client.subscribe("$SYS/#")
client = mqtt.Client()
client.on_connect = on_connect
client.connect("mqtt.eclipseprojects.io", 1883, 60)
You may also want to consider the advice in this answer (as per the comment from #mnikley) because that way the broker will queue up messages for you while the connection is down (otherwise these will be lost).
I am working with a device that publishes to the topic test/123, where 123 is the name of the device. I need to subscribe to that topic (and processes received messages); in addition I also need to send a word to the same topic (test/123). The device only looks at this topic.
How can I distinguish between incoming and outgoing by content? More precisely, how to send correctly. In the on_message method you need to do this or you need to create another method, but then how to receive incoming messages there. From the incoming messages I need to get the name of the device and then work with it.
import paho.mqtt.client as mqtt
import paho.mqtt.publish as publish
# The callback for when the client receives a CONNACK response from the server.
def on_connect(client, userdata, flags, rc):
print("Connected with result code "+str(rc))
# Subscribing in on_connect() means that if we lose the connection and
# reconnect then subscriptions will be renewed.
client.subscribe("/test/#")
# The callback for when a PUBLISH message is received from the server.
def on_message(client, userdata, msg):
print(msg.topic+" "+str(msg.payload))
imei = msg.topic.split('test/')[1]
data = msg.payload.decode()
print(imei)
print(data)
publish(imei)
def publish(imei):
client = mqtt.Client()
user = 'test'
passw = '1111'
client.username_pw_set(user,passw)
client.connect("localhost",1883)
topic = '/test/'+ imei
client.publish(topic,'hello')
print('SEND')
client.disconnect()
client = mqtt.Client()
user = 'test'
passw = '1111'
client.username_pw_set(user,passw)
client.on_connect = on_connect
client.on_message = on_message
client.connect("localhost", 1883, 60)
client.loop_forever()
MQTT does not differentiate between clients in any way, that means if a client subscribes to a given topic it will receive ALL messages on that topic, including the ones it publishes it's self. So with your current design you will always get the message you publish in response to the first message back and this will trigger re-sending that message.
MQTT messages do NOT contain any information about who published the message unless you choose to add it to the payload, so you have no way to identify the incoming message as being the one you just published and this will cause a message loop storm.
The CORRECT solution is to not use the same topic for the 2 messages.
MQTT v5 has a flag that can be passed as part of establishing the connection
which prevents messages being returned to the client that published them. At this time it does not appear that the Paho Python library has a way to set this flag.
If you are using MQTT v3.1.1 and the mosquitto or RSMB MQTT broker then there is an undocumented option (this is not part of the MQTT spec) that can be set which will also prevent messages being returned. The following code will ONLY work with the 2 brokers I have mentioned.
import paho.mqtt.client as mqtt
# The callback for when the client receives a CONNACK response from the server.
def on_connect(client, userdata, flags, rc):
print("Connected with result code "+str(rc))
# Subscribing in on_connect() means that if we lose the connection and
# reconnect then subscriptions will be renewed.
client.subscribe("test/#")
# The callback for when a PUBLISH message is received from the server.
def on_message(client, userdata, msg):
print(msg.topic+" "+str(msg.payload))
imei = msg.topic.split('test/')[1]
data = msg.payload.decode()
print(imei)
print(data)
publish(client, imei)
def publish(client,imei):
topic = 'test/'+ imei
client.publish(topic,'hello')
print('SEND')
client = mqtt.Client()
user = 'test'
passw = '1111'
client.username_pw_set(user,passw)
client.on_connect = on_connect
client.on_message = on_message
client.enable_bridge_mode()
client.connect("localhost", 1883, 60)
client.loop_forever()
p.s. do not start topics with a leading / while legal according to the spec, it will break things like shared subscriptions and adds an extra null to the start of the topic tree.
I am sending a number of messages simultaneously from multiple clients from one python script and trying to receive them on another script. The problem I am getting is that the message is received but only from the first client that gets connected and it keeps on looping over it.
What I need to have is that I get messages from each client in the manner they are published.
import paho.mqtt.client as mqtt
import time
def on_connect(client, userdata, flags, rc):
if rc == 0:
print("Connected to broker")
global Connected
Connected = True
else:
print("Connection failed")
def on_message(client, userdata, message):
print ("Message received: " + str(message.payload) + " from " + str(client))
Connected = False
client = mqtt.Client()
client.on_connect= on_connect
client.on_message= on_message
client.connect(host)
client.loop_start()
while Connected != True:
time.sleep(0.1)
client.subscribe("test")
print("subscribed")
client.loop_stop()
You are misunderstanding what the client argument in the on_message callback is.
This value is a link to the local instance of the MQTT client that has subscribed to the topic.
MQTT messages do not carry any information about the client that published them, unless you explicitly encode it into the payload. Part of the point of a Pub/Sub protocol like MQTT is to totally decouple the information creator (publisher) from the information consumer (subscriber).
Also you should move the call to client.subscribe("test") to inside the on_connect() callback because as you have it you are trying to resubscribe to the same topic 10 times a second which will achieve absolutely nothing, except to generate unneeded load on the broker.
Let me introduce my problem to you, first of all I have to say that i'm newbie at AWS and MQTT, I mean (don't be mad at me), my question: I want to publish through a MQTT client to AWS IoT/Lambda a simple JSON {'petition':'Hola', 'n':0}, and once published, the lambda function has to send back the JSON message {'petition': 'Mundo', 'n': 0} and it has to do it 10 times. The code works fine when u publish the message but it does not recive any. Please I need help to solve it.
Here's the squema:
DEVICE ---> MQTT ---> IoT SQL SENTENCE ---> AWS LAMBDA
DEVICE <--- MQTT <--- AWS LAMBDA
NOTE: the device is running in linux terminal and messages has to appear somehow on the screen.
AWS Lambda handler
import json
def lambda_handler(event, context):
# TODO implement
data={}
data["petition"]="Mundo"
data["n"]=event["n"]
mensaje = event['petition']
if mensaje =='Hola':
envio=json.dumps(data)
return data
else:
return 'nada encontrado'
IoT SQL SENTENCE
SELECT * FROM 'Hello_World'
NOTE: those 2 above are implemented using lambda function service.
DEVICE CODE
import paho.mqtt.client as paho
import os
import socket
import ssl
import time
import json
def on_connect(client, userdata, flags, rc):
print("Connection returned result: " + str(rc) )
# Subscribing in on_connect() means that if we lose the connection and
# reconnect then subscriptions will be renewed.
def on_message(client, userdata, msg):
print("topic: "+msg.topic)
print("payload: "+str(msg.payload))
data=json.loads(msg.payload)
if data["n"]<9 and data["petition"]=="Mundo":
data["petition"] = "Hola"
data["n"] = n+1
envio=json.dumps(data)
mqttc.publish(thingName, envio)
time.sleep(4)
def on_publish(client,userdata,missatge): #create function for callback
print("data published \n")
print "Create client instance"
mqttc = paho.Client()
mqttc.on_connect = on_connect
mqttc.on_publish = on_publish
mqttc.on_message = on_message
#mqttc.on_log = on_log
data={}
awshost = "a20u2bg4i3u0uq.iot.eu-west-2.amazonaws.com"
awsport = 8883
clientId = "39cfba3c326847909aa5f4544211f4a4"
thingName = "Hello_World"
caPath = "/#/rootCA.pem"
certPath = "/#/3218b320c9-certificate.pem.crt"
keyPath = "/#/3218b320c9-private.pem.key"
mqttc.tls_set(caPath, certfile=certPath, keyfile=keyPath, cert_reqs=ssl.CERT_REQUIRED, tls_version=ssl.PROTOCOL_TLSv1_2, ciphers=None)
print "connecting to browser"
mqttc.connect(awshost, awsport, keepalive=60)
mqttc.loop_start()
time.sleep(2)
print"subscribing...."
mqttc.subscribe(thingName)
print"subscribed"
time.sleep(2)
data["petition"]="Hola"
data["n"]=0
envio=json.dumps(data)
print(envio)
print "Sending..."
mqttc.publish(thingName, envio)
time.sleep(4)
print "Sent"
mqttc.disconnect()
mqttc.loop_stop()
I would really just set up an API call in API Gateway for your callback to the Lambda.
I have configured MQTT Broker, receiving published messages from another piece of code (not written or accessible by me). I added another topic to the broker configuration and am now trying to publish data to this new topic from a piece of python code. I get the feedback that the message is published by the callback function, but no actual data is received.
Is there anything I am missing?
I am using the following code:
import paho.mqtt.client as mqtt
import time
#=========================================================================
def on_connect(client, userdata, flags, rc) :
print "on_connect()"
#=========================================================================
def on_publish(client, userdata, mid) :
print "on_publish()"
#=========================================================================
def send() :
mqttc = mqtt.Client()
mqttc.on_connect = on_connect
mqttc.on_publish = on_publish
#host = "localhost"
host = "127.0.0.1"
port = 1883
keepalive = 60
print "\nConnect to '%s', port '%s', keepalive '%s'" % (host, port, keepalive)
mqttc.connect(host=host, port=port, keepalive=keepalive)
time.sleep(3)
mqttc.loop_start()
time.sleep(3)
topic = "data/MY/TOPIC"
msg = "MY_MESSAGE"
print "Publish to '%s' msg '%s'" % (topic, msg)
mqttc.publish(topic, msg, qos=2)
time.sleep(3)
mqttc.loop_stop()
# end send()
#=========================================================================
if __name__ == "__main__":
send()
# end if
Getting the stdout
Connect to '127.0.0.1', port '1883', keepalive '60'
on_connect()
Publish to 'data/MY/TOPIC' msg 'MY MESSAGE'
on_publish()
I am not sure if the loop() functions are necessary, but if I do not embed the publishing in the loop_start() and loop_stop(), I do not get a on_connect callback.
The loop functions are necessary as these are where all the network traffic is processed.
Manually setting up a connection to the broker to just send a single message like this is not a good idea, it would be better to start the client, leave it running (by calling loop_start() and not calling loop_stop()) in the background and then just call the publish method on the mqttc client object.
If you don't want to keep a instance of the client running then you should use the single message publish helper method provided by the paho python library (https://pypi.python.org/pypi/paho-mqtt/1.1#single):
import paho.mqtt.publish as publish
publish.single("paho/test/single", "payload", hostname="iot.eclipse.org")