Mastering Internet of Things

Understanding LWM2M server operations

When the servers are aware of the clients, they can begin to interact with them. First, they discover what objects, instances, and resources are available. This is done using CoAP GET method calls on the device, object, or object instance levels. The LWM2M returns CoRE Link Format Documents, describing available child CoAP resources.

Servers can then begin to read LWM2M resource values, by executing CoAP GET calls on the resources or resource instances. Typically, resources must support a simple binary content format that is relatively compact, called the Type-Length-Value, or TLV, format. Optionally, the device can also support JSON, based on SenML, and a plain text format. Since resources are RESTful, ...