Forums - MQTT With Max Payload Length

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MQTT With Max Payload Length
congngale
Join Date: 13 Jul 18
Posts: 3
Posted: Fri, 2018-07-13 10:51

Hi All,

I am developing a product base on QCA4010 which will receive a signal from IR module and send it to a Broker over MQTT protocol.

I have done with developing MQTT client to publish/subscribe message but I could not publish a message with payload length more than 400.

When I try to send a packet with size is 512 or 1024 the MQTT library return error -5 which is (PUBLISH_ERROR).

So, There is anyway to help me to get the MQTT client able to publish message with size more than 400.

Thanks,

Cong Nga Le

 

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jbhanu Moderator
Join Date: 6 Feb 17
Posts: 76
Posted: Wed, 2018-07-18 02:36

Hi , 

The maximum payload length of MQTT publish is 512 . It also includes Topic and thing name. 

Regards

Jyotiranjan 

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congngale
Join Date: 13 Jul 18
Posts: 3
Posted: Thu, 2018-07-19 03:58

Hi jbhanu,

Thank for your information. I have managed to only publish/subcribe message with payload length under 480 bytes then it is worked.

But, I face another problem which is the MQTT client disconnected and throw SOCKET_CLOSE error message if I receive round 8 - 10 messages.

I guess it is an issue in socket layer about buffering, do I have any way to verify and fix this problem?

Thanks,

Cong Nga Le

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jbhanu Moderator
Join Date: 6 Feb 17
Posts: 76
Posted: Thu, 2018-07-19 05:14

Ok. What is the size of each messages? 

 

Regards

Jyotiranjan 

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congngale
Join Date: 13 Jul 18
Posts: 3
Posted: Thu, 2018-07-19 08:49

Hi jbhanu,

I usually send 2 packet a time, with 452 bytes for first packet and 258 bytes for second packet. I have send multiple time which is around 8  to 10 times, in total I have sent 16 - 20 packets then the issue happens.

Thanks,

Cong Nga Le

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jbhanu Moderator
Join Date: 6 Feb 17
Posts: 76
Posted: Wed, 2018-07-25 10:48

Can you please try to reproduce the same with mosquitto broker locally and share me the steps. 

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