LwM2M Sever

LwM2M Server in SCEF acts as cross proxy converting the CoAP messages to HTTP messages and vice versa. It enables IP device communication between IoT devices and SCS/AS.

Server enables LwM2M protocol based IoT device communication for following use cases:

• Access Control
• Device Management
• Connectivity
• Firmware Update
• Location
• Connectivity Statistics

LwM2M server enables SCEF to be used for following transport bindings:

• UDP and DLTS

LwM2M server provides unified T8 interface towards SCS A/S to handle communication with LwM2M devices. Refer to LwM2M Server Configuration for more details on LwM2M configuration.

Following section explains the processes managed by LwM2M server and Device.

LwM2M Device Registration

When LwM2M device is registered, LwM2M Server sends a notification to configured SCS/AS Url. You can add/delete/list the SCS/AS urls based on device id or domain id.

Figure 2-18 LwM2M Device Registration

LwM2M Event Subscription Process

SCS/AS sends monitoring event subscription message to API Gateway to monitor a device resource. If the device is not registered for which the subscription request is received, HTTP 404 Device not found error is returned.

If the device is registered in LwM2M server, then LwM2M observe message is sent to Device. A unique subscription identifier is generated by server and returned in response.

Figure 2-19 LwM2M Event Subscription Process

LwM2M Event Subscription Notification Process

When device send notification to the observe request, the stored subscription request will be fetched and notification request will be generated and sent to the callback Url sent in subscription request.

Figure 2-20 LwM2M Event Subscription Notification Process

LwM2M Event Subscription Delete Process

SCS/AS can send HTTP Delete message to stop monitoring of the device resource. If the subscription ID sent is wrong then HTTP 404 error code is returned.

If the subscription ID sent is correct then LwM2M cancel request is sent to Device to stop the observation.

Figure 2-21 LwM2M Event Subscription Delete Process

LwM2M Data Delivery Process

SCS/AS can send data to LwM2M device using Nidd Downlink Data transfer request. When the Downlink data transfer request is sent LwM2M server will send corresponding LwM2M message to the device. If the device is not registered with the server then HTTP 404 message should be returned.

Figure 2-22 LwM2M Data Delivery Process