In theory you should be able to do that with lwm2m :
* Our devices do continuous measurement of sensor values
=> you should use LWM2M observe
* All values have to be transmitted to the server.
=> you should use CON message for observe response (This is
CoAP concept)
* Data should be transmitted in chunks to keep network traffic
down.
=> you should use QueueMode + JSON + historical
representations( also called notification storing) + CoAP
block-wise
* All data chunks should be stored on device until receipt is
acknowledged by server.
=> Already said, CON message for acknowledgement, QueueMode +
json + historical representations for chunks, CoAP block-wise if
your chunk is too large.
One detail, be aware that you can not observe several object in
one request. And when you observe an object you should send the
complete object on each notification (even if only one resource
changed)
(see :
https://github.com/OpenMobileAlliance/OMA_LwM2M_for_Developers/issues/76)
There is a lot of specification wording. Please read
specifications if its not clear :
http://openmobilealliance.org/release/LightweightM2M/V1_0-20170208-A/OMA-TS-LightweightM2M-V1_0-20170208-A.pdf
https://tools.ietf.org/html/rfc7252
https://tools.ietf.org/html/rfc7641
https://tools.ietf.org/html/rfc7959
(sry about that :/)
In pratice :
=> I don't know if historical representations is well supported
by lwm2m implementation. (At leshan this is only supported at
server side)
=> There is some issue with observe + NAT.
https://github.com/OpenMobileAlliance/OMA_LwM2M_for_Developers/issues/171
=> Be aware that LWM2M currently run over UDP.
To conclude :
if you need interoperability, device management and the
limitations above is not blocking for you, you can consider LWM2M.
If not, you should maybe consider to use MQTT over TCP (be aware
I'm not an expert about MQTT). If you really need UDP, you can
consider to just use a CoAP POST/PUT at client side (probably with
block wise as your chunk can be large)
HTH
Simon
Le 02/03/2017 à 09:23, Martin Scheffler
a écrit :
Hi folks,
sorry if this is not the right mailing list for this, maybe
you can point me at a better place to discuss this?
I am currently evaluating Leshan for use in our upcoming
projects, but I am not sure how to achieve this with Lwm2m:
* Our devices do continuous measurement of sensor values
* All values have to be transmitted to the server
* Data should be transmitted in chunks to keep network traffic
down
* All data chunks should be stored on device until receipt is
acknowledged by server.
Can this be achieved with Lwm2m? Or would maybe a different
protocol be a better fit here?
Thanks for your help!
Martin Scheffler
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