6
votes
Accepted
MQTT packet validity check
The message above decoded:
MQIsdp{03}{02}{00}{14}{00}{11}evolan_12345678900!{00}{06}evolanHello eevoLAN!à{00}
It is mixed Ascii/Hex (topic, clientID and payload are plain ascii, special chars are {...
- 221
6
votes
Accepted
The MQTT Paho Python code doesn't work properly
Change the last line from
client.start_loop()
To
client.loop_forever()
- 12.7k
5
votes
Questions about MQTT max message size
First question:
The payload of the message is limited to 268,435,456 bytes (256Mb) (see the Stack Overflow question What is the maximum message length for a MQTT broker?)
Your second question doesn'...
- 12.7k
4
votes
Accepted
How to process the MQTT queue once?
Retained messages will only be delivered once (per connection).
And there can only be 1 retained message on a given topic at any one time.
So just connect, start the loop and subscribe to the topics ...
- 12.7k
4
votes
Accepted
MQTT messages hit queued or inflight limits, is it stated somewhere it's the oldest messages that are dropped?
The code that handles the max_queued_messages is here
if self._max_queued_messages > 0 and len(self._out_messages) >= self._max_queued_messages:
message.info.rc = MQTT_ERR_QUEUE_SIZE
...
- 12.7k
3
votes
Accepted
How to cross compile Paho-MQTT-C library for ARM?
You are facing these build errors as you are missing the sysroot corresponding to the arm-gcc that you are using as your CC.
You may try changing the Makefile as follows:
diff --git a/Makefile b/...
- 2,620
2
votes
Accepted
Make connection between react native & raspberry & MQTT
We solved this by edit the Mosquitto config file to either add a new listener port 8883 and to use the WebSocket protocol for that port.
From Stack Overflow: Seting mosquitto broker to listen on two ...
- 179
2
votes
Python Paho MQTT 2.5 KB messages not sending for days, while 0.1 KB messages send fine
There may be paths with a MTU of 1280 in the way. Try 1100 or 1200 and see if that fixes it.
If not, try to find an MTU finder app to try to find the MTU to your destination from your source.
- 1,198
2
votes
Accepted
Python Paho MQTT 2.5 KB messages not sending for days, while 0.1 KB messages send fine
Based on what we've seen in the comments and edits, I think it might be worth setting a lower MTU for the cellular link.
Try running something like the following:
nmcli con mod "user_apn" ...
- 12.7k
2
votes
Accepted
Python Paho MQTT doesn't work via LTE
The Paho Python library will work just fine via LTE. The library is built to interact with the OS's TCP/IP stack. It has no knowledge of the underlying hardware of how that TCP/IP stack talks to the ...
- 12.7k
2
votes
Accepted
Unable to publish MQTT server in an infinite while loop in Python script
You should not be running long running (infinite loops) in the callbacks.
All the callbacks run on the client network thread's main loop (the one started by client.loop_forever()).
This means if the ...
- 12.7k
2
votes
Accepted
Publish image data to MQTT not showing
This is because the message payload is way bigger than will fit into a single TCP packet so the problem is that you are not starting the Paho client network loop which will chunk the message up and ...
- 12.7k
2
votes
Make connection in the background & closed app using MQTT
The only way to make sure notifications are shown is to use a server and the relevant platform’s push notifications.
You’ll have a hard time keeping a process running, active, and connected in the ...
- 2,358
1
vote
Make connection in the background & closed app using MQTT
I'll start with saying I've never worked with React or React Native.
But you are going to need what Android calls a Background Service to run the MQTT client in so it can stay alive in the background. ...
- 12.7k
1
vote
Accepted
How to handle the connection in MQTT using Paho
const client = new Paho.MQTT.Client(process.REACT_APP_HOST, Number(process.REACT_APP_PORT), clientID);
client.onConnectionLost = this.onConnectionLost;
client.onMessageArrived = this....
- 138
1
vote
Accepted
Determine state before publish
I suggest you store it in a local variable and then start a time which will time out after a period longer than the expected response time.
If the local variable is set and the button is pressed again,...
- 12.7k
1
vote
MQTT subscribing is not working
Just a flash from the past as I was trouble shooting this same issue, you need to have a unique name on the mqtt object created
client = paho.Client("local_test")
If you have multiple ...
- 11
1
vote
MQTT subscribing is not working
As others have mentioned/implied in the comments:
The actual sequence that is supposed to happen is:
Setup your callbacks correctly first (including the on_message).
Call connect.
Wait until you get ...
- 1,198
Only top scored, non community-wiki answers of a minimum length are eligible