nrf9160 - MQTT over TLS - Socket buffer limit - AWS Shadow - Nordic Team Proposal

[ReneDelgado]

Hi,

Currently, we work on a project that uses:

    nRF9160
    Zyphre OS
    Segger Embedded Studio for  Arm (Nordic Edition) V5.10d
    SDK v1.4.1
    mqttlib.

According to the documentation, it is not possible to send or receive messages larger than 2K with MQTT / TLS. So our question is:

What is the official proposal of the Nordic Team to be able to use AWS Shadow with MQTT / TLS in the nrf9160?

Thank you,

Dagtus Team.

[ReneDelgado]

Hello,

There is any update?

Thanks a lot,

René D.

[Hakon]

Hey,

What is the official proposal of the Nordic Team to be able to use AWS Shadow with MQTT / TLS in the nrf9160?

Have you looked at the AWS IoT sample? It publishes to the device shadow, using MQTT over TLS.

 

[ReneDelgado]

Hello,

that example is where our question came from because AWS shadow can send JSON messages up to 8k. If we send a message of that size to the example that you attached, the socket will be disconnected. Is there a proposal to support 8k messages over TLS?

Thank you.

René D.

[Hakon]

Is it possible that you are getting disconnected from AWS because of the policy? You can try using the policy below just for testing to see if it still gets disconnected.

{
     "Version": "2012-10-17",
     "Statement": [
         {
           "Effect": "Allow",
           "Action": "iot:*",
           "Resource": "*"
         }
      ]
   }

The policy allows all MQTT traffic on the broker. You should not use this policy in the final solution, just for testing purposes. This is due to security reasons.

[Dmitry Pogodin]

Hey,

any updates on this issue? I'm experience the same problem. When shadow size is more than 5k, I've got disconnected from AWS cloud. When shadow is small - every thing is working, so it's not related to AWS side.

My observations shows the following: after sending request for shadow, in aws_iot.c, in aws_iot_cloud_poll thread we receive signal that there something received in the connected socket. We call aws_iot_input() which in turn call mqtt_input(). mqtt_input() call client_read() which call mqtt_handle_rx() and if there is an error, calls client_disconnect() (which is our case). mqtt_handle_rx try to read first header of the message (2 bytes), but for unknown for me reason reading from the socket returns 0 bytes and therefore initiate disconnection sequence.

I use SDK v1.6.0 and Segger. My board is nRF9160.