Send file to server over CoAP ?

[A. Mullot]

Hi,

I am currently doing a project where I need to send files (from 50 to 300kB) to a server using nRF9160. I'd like to know which protocol would be more suitable to do this.

I was thinking of CoAP, because I don't need to have a constant connexion like with MQTT. However, I could not find documentation about if it possible, and if so how to do it. Maybe you could help me there ?

Thanks.

Kind regards,

Armand

[Achim Kraus]

General, CoAP (RFC 7252) has an extension called "blockwise" (RFC 7959), which sends larger payload in single blocks.

In your case, if you use it for a PUT or POST, you need to test, if that works "reliable" enough. Mainly because many server-side blockwise implementations are only considered for smaller transfers with a couple of blocks, and not for larger ones, which may come with some breaks and resumptions.

[A. Mullot]

Hi,

Thank you for the answer. I'll start by taking a look at this blockwise extension.

Kind regards, 

Armand

[A. Mullot]

Actually, I realized that I could also send files through http, once that the device has a LTE or NB-IoT connection. I'm currently investigating this way of doing it, I'll let you know how it goes.

I'm using the https_client sample, and trying to modify the request.

[Achim Kraus]

You may check some limits of such a http request. Not that you can't use it for more than say 10k.