I study about IoT protocol CoAP, MQTT, LwM2M.
I was able to know a little about CoAP and MQTT.
But I do not know what LwM2M is.
I do not know what's different from CoAP.
I just thought that LwM2M is not a protocol with some format but a system structure using CoAP.
Is that correct?
What is LwM2M and How Can I know more information about LwM2M?
Please someone teach me.
LwM2M (specified by OMA) is a is a protocol group largely built on top of CoAP (specified by the IETF).
LwM2M uses a subset of CoAP's capabilities that fit into an architecture of many small devices registering at a large LwM2M server that manages the devices. It prescribes particular path structures (that numbers are used in paths, and what they mean) that represent the LwM2M object model to allow that unified management.
Compared to "plain CoAP", this limits the scope of what devices can do. Devices can still provide other CoAP functionality on the same server that is not covered by LwM2M. Those limitations allow different vendors to build devices that can interoperate with a different management servers, and LwM2M provides additional specifications for easy deployment (e.g. based on smart cards) that are out of scope for CoAP.