MQTT over websocket in python

Question

is there any support in python to subscribe on mqtt broker with port 8080

 import sys
 import paho.mqtt.client as mqtt

 def on_connect(mqttc, obj, flags, rc):
     print("rc: "+str(rc))

 def on_message(mqttc, obj, msg):
     print(msg.topic+" "+str(msg.qos)+" "+str(msg.payload))

 def on_publish(mqttc, obj, mid):
     print("mid: "+str(mid))

 def on_subscribe(mqttc, obj, mid, granted_qos):
     print("Subscribed: "+str(mid)+" "+str(granted_qos))

 def on_log(mqttc, obj, level, string):
     print(string)

 mqttc = mqtt.Client()   
 mqttc.on_message = on_message
 mqttc.on_connect = on_connect
 mqttc.on_publish = on_publish
 mqttc.on_subscribe = on_subscribe
 mqttc.connect("test.mosquitto.org", 8080, 60)
 mqttc.subscribe("test/iot", 0)

 mqttc.loop_forever()

i can not connect with this code. Mosquitto has websocket support at port 8080 but this paho library does not work for it. any solution for python? i am using python 2.7 on windows 10.

Answer 1

The Paho MQTT module introduced websocket support some days ago. I don't think it is released yet, but you can install from the master under Linux branch using

pip install git+git://github.com/eclipse/paho.mqtt.python.git

Also works under windows. (Thanks for info from the comments)

You can use the websockets as transport by connecting with

mqttc = mqtt.Client(transport="websockets")

UPDATE:

If you try to use the websocket protocol with the python client because you also need to connect a browser client (for example MQTT.js) then you can also configure mosquitto to listen to websockets and the normal mqtt protocol .

Simply create a configuration file for example in

/etc/mosquitto/mosquitto.conf

with the following contents:

listener 1883
protocol mqtt

listener 9001
protocol websockets

Then you can then run mosquitto with

mosquitto -c /etc/mosquitto/mosquitto.conf

You should see similar output:

1469015320: mosquitto version 1.4.8 (build date 2016-05-3112:07:40+0200) starting
1469015320: Config loaded from /etc/mosquitto/mosquitto1.conf.
1469015320: Opening ipv4 listen socket on port 1883.
1469015320: Opening ipv6 listen socket on port 1883.
1469015320: Opening websockets listen socket on port 9001.

Your python client then connects to port 1883 and the browser client to 9001

You can use what-mqtt browser client to test the websocket listener. Just point it to ws://localhost:9001

Answer 2

Between Feb and now the paho.mqtt.python codebase has been fixed. Just add transport='websockets' as Fl0v0 suggested, it simply works. Below is the full code which subscribes to everything or everything under $SYS/ . The code tested is on the master branch with commit hash e56f913 on June 3 of 2016.

#!/usr/bin/python

import sys
import paho.mqtt.client as mqtt

def on_connect(mqttc, obj, flags, rc):
    print("rc: "+str(rc))

def on_message(mqttc, obj, msg):
    print(msg.topic+" "+str(msg.qos)+" "+str(msg.payload))

def on_publish(mqttc, obj, mid):
    print("mid: "+str(mid))

def on_subscribe(mqttc, obj, mid, granted_qos):
    print("Subscribed: "+str(mid)+" "+str(granted_qos))

def on_log(mqttc, obj, level, string):
    print(string)

mqttc = mqtt.Client(transport='websockets')   
mqttc.on_message = on_message
mqttc.on_connect = on_connect
mqttc.on_publish = on_publish
mqttc.on_subscribe = on_subscribe

mqttc.connect("test.mosquitto.org", 8080, 60)

mqttc.subscribe("#", 0)
#mqttc.subscribe("$SYS/#", 0)

mqttc.loop_forever()

Update: The code above does not work on Windows 7 with python 2.7.6 that I tested with, by invoking from one version of Cygwin (not the cygwin python though). None of the topic "#" or "$SYS/#" gives any published message back.

Instead, pub or sub to solid topics works as the example follows. Patch paho.mqtt.python examples/pub-single.py and examples/sub-simple.py . Then run sub-simple.py in one terminal. Run pub-single.py in another terminal, twice. The subscriber terminal will print out two messages published by the publisher.

Patch to examples/pub-single.py :

-publish.single("paho/test/single", "boo", hostname="test.mosquitto.org")
+publish.single("/HelloWorld", "boo", hostname="test.mosquitto.org",
+               port=8080, transport='websockets')

Patch to examples/sub-simple.py :

-topics = ['#']
+topics = ['/HelloWorld']

-m = subscribe.simple(topics, hostname="iot.eclipse.org", retained=False, msg_count=2)
+m = subscribe.simple(topics, hostname="test.mosquitto.org",
+                         retained=False, msg_count=2,
+                         port=8080, transport='websockets')

Answer 3

No, the Python version of the Paho library does not support MQTT over Websockets.

In fact I believe the only native client side (not in a browser) MQTT library that supports MQTT over Websockets is the NodeJS module ( https://www.npmjs.com/package/mqtt )