size of the messages

[maurycy szmurlo]

Hi

I'm evaluating MQTT with VerneMQ for a project since few days so sorry if the question is trivial. Provided that the length of the topic is T bytes and the length of the message is M bytes, what is the length of the total network message ?

Thanks in advance for your feedback

Maurycy

[André Fatton]

Hi Maurycy,

For an MQTT PUBLISH frame you're looking at a 2 byte fixed header, a variable header and a payload.

https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718037 should help you. The fixed header indicates the remaining length. You can also use Wireshark (enabling MQTT parsing) to look into the MQTT frames.

André

[maurycy szmurlo]

clear.

thanks