Can device act as CoAP service and client at the same time?

RE: Can device act as CoAP service and client at the same time?

ArunRuchir — Mon, 07 Apr 2025 09:47:38 GMT

Thanks Achim.

Can some one help if they have done or can do this combined CoAP Client and Server functionalities ? Pls help.

Regards

Arun

RE: Can device act as CoAP service and client at the same time?

Achim Kraus — Fri, 04 Apr 2025 05:59:39 GMT

In general, UDP sockets are always acting as server&client at the same time. CoAP messages are also designed to act as both request and response, the only difference is the contained code, 0.xy is a request, 2.xy a success response, 4.xy a client error, and 5.xy a server error. So, it's easy to send&receive UDP massage with the same socket, you pass the received messages to the parser and then you check the code and split it.

I just don't know, if the zephyr's coap client&server are able to do so, I mainly use the message encoding and parsing, but not the message handling of zephyr.

RE: Can device act as CoAP service and client at the same time?

ArunRuchir — Fri, 04 Apr 2025 05:02:18 GMT

Hi,

Upon searching I got this and have some specific need to make CoAP Server send some very specific data to OTBR (or other server). This will be once in a while and not regular.
So,can some one guide how to make a CoAP Server becoming CoAP client momentarily and back to server ?

Regards

Arun

RE: Can device act as CoAP service and client at the same time?

Achim Kraus — Sun, 11 Feb 2024 10:59:14 GMT

For CoAP in general, that's possible and called "role-exchange". The message format for request and responses is the same, only the "code" uses different values for requests and responses. But I don't know, If the specific implementation used there supports it.