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6.5 LwM2M Server Interactions

6.5.0 Introduction

This clause describes how the IN-CSE interacts with a LwM2M Server in order to manage the devices. The interaction between the IN-CSE and the LwM2M Server includes the followings:

  • Communication session establishment.
  • Translations for requests/responses and notifications between the oneM2M service layer and the LwM2M protocol.
  • Discovery of the LwM2M Objects in the device and Management Resources in the IN-CSE.

Note

The LwM2M Server interaction is applicable to the case that the LwM2M Server is external to the IN-CSE.

6.5.1 Communication Session Establishment

The communication session can be initiated by the IN-CSE or by the LwM2M Server. The IN-CSE can initiate the communication session if the IN-CSE needs to interact with the LwM2M Objects in the device through the LwM2M Server (e.g. an IN-AE sends firmware update Requests by using the [firmware] Resource in the IN-CSE). On the other hands, the LwM2M Server can initiate the communication session if the LwM2M Server detects changes of LwM2M Objects that the LwM2M Server manages or needs to notify events to the IN-CSE that occurred in the device. In this case, the notifications of LwM2M Object changes or events can be limited to the cases that the IN-CSE has expressed interests.

The multiple communication sessions can be established between the IN-CSE and the LwM2M Server depending on the communication environments and the protocols to be used for the communication session.

6.5.2 Translation of Requests and Responses between IN-CSE and LwM2M Server

The present document specifies how oneM2M service layer protocol regarding the device management shall be mapped to OMA LwM2M protocol. The interaction between the IN-CSE and the LwM2M Server lies between these two protocols and the Requests/Responses from those two protocols shall be properly translated by the interactions between the IN-CSE and the LwM2M Server. The Requests/Responses translations between the IN-CSE and the LwM2M Server may be done in any way that satisfies the procedure mappings specified at the clause 6.4.

6.5.3 Discovery and Subscription for LwM2M Objects

Being triggered by oneM2M service layer, the interactions between the IN-CSE and the LwM2M Server can provide the following functionalities:

  • Discovery of LwM2M Objects in the devices of interest.
  • Subscription to LwM2M Objects for being notified for the interested events.

With the discovery and the subscription to the LwM2M Objects in the device, the IN-CSE can be capable to synchronize the <mgmtObj> Management Resources with LwM2M Objects in the device.

6.5.4 Access Control Management

For a device under managements, the IN-CSE can have multiple LwM2M Servers that can connect to the device. When receiving the oneM2M Service Layer Requests, the IN-CSE shall first authorize the Request based on the <accessControlPolicy> resource associated with the addressed <mgmtObj> resource, Then, among those LwM2M Servers, when receiving the oneM2M service layer Requests, the IN-CSE needs to select the proper LwM2M Server that can successfully perform the received Request based on the access rights that each LwM2M Server has. The interaction between the IN-CSE and the LwM2M Server may be used to discover the access control that the LwM2M Server has for the target device. The LwM2M Server is agnostic of the identity or roles used in the service layer.