Re: CoAP client observer

Lubos, Robert

Hi Alessio,


Unfortunately I’m not aware of any other good resource for the client side of the Zephyr Observer API other than `coap_client` sample. When checking the sample though I’ve noticed that indeed it might be confusing for the users, as the observer part was oversimplified IMO, and not fully RFC-compliant.


I’ve posted a PR ( which aims to improve the sample in this regard – it now shows how to register a response callback, which will be called for each notification.





From: users@... <users@...> On Behalf Of Alessio via
Sent: sobota, 27 listopada 2021 16:35
To: users@...
Subject: [Zephyr-users] CoAP client observer


Dear Sirs,

can anyone point me to some docs to read, some code examples or some tutorial about CoAP observer?


Starting from CoAP client example, I'm stuck in a point where I, from a client, can ask to a server to observe a topic but I never get notified about changes. Data packages are sent from the server (I can see that with wireshark) but seems that the callback is never called. Maybe I'm missing something...



Alessio Galliazzo


Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it.
    - Brian W. Kernighan

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