Re: [lwip-devel] Callbacks in MQTT

[Ganesh Thambhahalli Satyen]

Hi,

A gentle reminder.

Regards,

Ganesh

 

From: Ganesh Thambhahalli Satyen
Sent: 09 August 2022 11:43
To: lwip-devel@nongnu.org
Subject: FW: Callbacks in MQTT

 

 

 

From: Ganesh Thambhahalli Satyen
Sent: 01 August 2022 13:10
To: 'lwip-users@nongnu.org' <lwip-users@nongnu.org>; erian747@gmail.com
Cc: Dhanashree Mohite <dmohite@mathworks.com>
Subject: RE: Callbacks in MQTT

 

Hi,

As mentioned in the previous mail, we are trying to use the MQTT application present in LWIP along with a local Mosquitto broker. The callbacks  provided in the detailed description here - lwIP: MQTT client (nongnu.org) are being used.

 

In mqtt_connection_cb, it can be seen that the connection state needs to be MQTT_CONNECT_ACCEPTED for the the mqtt_set_inpub_callback to be called which in turn will call the incoming_publish and incoming_data callbacks which are needed for the subscribe data.

 

As per our observation, in the example_do_connect function, the connection state post mqtt_client_connect call is TCP_CONNECTING and not MQTT_CONNECT_ACCEPTED. Further, mqtt_connection_cb is not entered. This leads us to ask the following questions:

1. When is the mqtt_connection_cb called?
2. In mqtt_client_connect it can be observed that the connection state is manually set to TCP_CONNECTING. Thus, does it imply that the connection state needs to be manually set to another state?
3. What is the flow for the connection state to reach MQTT_CONNECT_ACCEPTED?

Eagerly awaiting your response

Regards,

Ganesh

 

From: Ganesh Thambhahalli Satyen
Sent: 28 July 2022 13:47
To: lwip-users@nongnu.org
Cc: Dhanashree Mohite <dmohite@mathworks.com>
Subject: Callbacks in MQTT

 

Hi,

We are trying to use the MQTT application present in LWIP along with a local Mosquitto broker. As per the documentation, the connect callback is supposed to be called after the connection goes through. We are not able to replicate the same when we utilise the detailed description provided here -  lwIP: MQTT client (nongnu.org). The client gets connected, but the callback is not entered. The conclusion that the callback is not entered is based on the flags we have added at the start and end of the callback. Is there any parameter change/ change in the order of calling which needs to be done?

Eagerly awaiting your response

Regards,

Ganesh