mosquitto

What is MAX message SIZE supported by Mosquitto / MQTT?

Asked by Lynton Grice

Hi there,

Forgive me if I am asking a stupid question as I have only just installed Mosquitto and did a very basic PUB / SUB using the "mosquitto_pub" and "mosquitto_sub" respectively.

I tried to send a 10MB PDF file to the subscriber but it onlt seemes to receive 3272 BYTES......

Here were my commands:

mosquitto_pub -t test/topic -f ./test.pdf

mosquitto_sub -t test/topic -q 1

What is the maximum message size that Mosquitto and MQTT support in general? If I can increase it to say 20MB's can you please let me know where I can do this?

Thanks for the help, much appreciated ;-)

Lynton

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Lynton Grice
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Roger Light (roger.light) said : 		#1

The maximum message size is around 260MB so you're well within that. I suspect the problem you're seeing is that mosquitto_sub really only works for text messages. If you examine the pdf file it's quite likely that byte 3273 is equal to 0, so mosquitto_sub sees it as the end of a string and stops printing.

If you want to do file transfer, I'm afraid you'll have to write your own client for the moment.

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Lynton Grice (lynton-grice) said : 		#2

Hi Roger,

That is super....I was being stupid, I have been bitten by that '\0' many times before, sorry about that ;-)

I just sent a 34 MB message happily to a subscriber...great!

260 MB's is more that enough for now.....

Thanks again

Lynton