In LwM2M, the information exchange occurs between the Server and the Client (which is located on a device).
There are 4 interfaces governing the communication:
Device Management and Service Enablement
The Bootstrap interface is used to provision the Client with information needed to “register” with the Server. Once the Client has been provisioned, it can then perform the registration via the second interface (Client Registration). Once the Client is registered, the last two interfaces can be used. The Device Management & Service Enablement Interface is used to access Client’s resources with simple operations such as “Write”, “Delete”, “Execute” and the like.
Finally the last interface – Information Reporting is used by a Server to receive notifications when the value of a specified resource has been changed. This can be used to pro-actively monitor the values of certain parameters, adjusting the thresholds to fit each specific use case, per device and in bulk.