CloudMQTT | simple client to interact with the CloudMQTT management | REST library

You have not started the MQTT client network loop so it will not be able receive messages or send a message large the the MTU.

You will also get disconnected after the keep alive period.

Add client.loop_start() before the call to client.connect()

or insert client.loop() after the time.sleep(5000) in the loop in main and it will be better to make it 1000 to the client loop runs at least once a second.

Adding sleeps in callbacks is normally a bad idea as it doesn't stop events from being triggered it just delays them, because they will just be queued up until the sleep times out.

You should set a flag on the first event just after sending the MQTT message which you can then expire using the While True loop in main. If a new event comes in while the flag is still set then you just don't send another MQTT message.

Try to get rid of strings, they will fracture your heap and cause crashes. Define global fixed charBuffers (big enough to take the largest message) and helper (tmp chars) for conversion and other things) Do not define const chars in the loop do it before setup so the compiler places them in the stack and is not using heap during runtime. I changed your code to this principle and added an extra delay between messages:

You are trying to force a native MQTT connection using the mqtt:// schema for the broker URL.

The problem is when the ReactJS code runs in the browser it can't use native MQTT (because of the browser sandbox), you need to use MQTT over Websockets.

You do this by changing the URL schema to wss:// (MQTT over Secure Websockets) and change the port number. The Cloudmqtt docs say the port will be 36987 rather than 16987.

You should be able to use MQTT over Websockets from NodeJS as well as ReactJS.

Given the asynchronous nature of the shown code, the syntax should be

So it was not working when trying to connect to the cloudMQTT server, but when I connected to my MQTT server or the test MQTT server, it worked. There must be an issue dealing with the protocol that the cloud mqttServer uses (MQIsdp) as apposed to the standard MQTT protocol that a normal MQTT server utilizes. I made a change to the connect packet so that it specified the MQTT protocol and pointed the TCP connection to the test server ( test.mosquitto.org ) and I can now Connect and Publish successfully.

For anyone who is just starting out with trying to interface an Arduino with a module like a SIM900 ( GPRS/GSM module ) to a MQTT server, I suggest you grasp a full understanding of standard AT Commands ( To establish a solid TCP connection to server ), how to compile the packets that will be sent through the GPRS module from the Arduino and lastly I suggest not using any code you have not written to achieve this. Learn how to establish the TCP connection with AT commands, then learn how to compile and send a connect packet by compiling the byte array yourself and sending it. Once you understand the packets and the communication between the client and the server, the MQTT world is your oyster.

You can use this code as a guideline but please try write as much of your own as possible: