8.2 Organization of Semantically Enabled Content Sharing Resources

8.2.1 Introduction

Semantically enabled Content Sharing Resources represent the structure and content of LWM2M Objects and Object Instances by translating LWM2M Objects, Object Instances and their LWM2M Resources and LWM2M Resource Instances into a hierarchy of Content Sharing Resources using the Content Sharing Resource's parent-child relationship described in oneM2M TS-0001 [2]. In addition, the LWM2M Resources values are contained within the <contentInstance> resource for <container> resources.

When the LWM2M Resource is of type LWM2M Object Link, the <contentInstance> resource that represents the LWM2M Resource is used to represent the LWM2M Object Link by assigning the destination of the LWM2M Object Link reference to another LWM2M Object's Content Sharing Resource. The reference is assigned using the <contentInstance> resource's contentRef attribute where the name of the attribute is "ObjectLink" and the value of the attribute is the URI of the destinaton Content Sharing Resource.

Figure 8.2.1-1: Relationships of LWM2M Semantically Enabled Content Sharing Resources

8.2.2 Lifecycle of Semantically Enabled Content Sharing Resources

Clauses 6.3 and 6.4 describe how LWM2M Objects and Object Instances are discovered and instantiated. The Semantic Interworking function uses these procedures for instantiation of the Content Sharing Resource for the LWM2M Objects and Object Instances.

The Content Sharing Resources for LWM2M Resources and Resource Instances are created as child resources of the parent Content Sharing Resource when the LWM2M Object and Object Instance are created. Likewise these child Content Sharing Resources are deleted when the parent Content Sharing Resource is deleted.

Creation, update or deletion of one or more <contentInstance> resources for the LWM2M Resource or Resource Instances that are not caused by the creation or deletion of the parent LWM2M Object or Object Instance Content Sharing Resource maps to the following operations on the LWM2M Client.

Table 8.2.2-1: LWM2M Resource Content Sharing Resource Lifecycle Translation

LWM2M Operation Device Management & Service Enablement Interface	oneM2M Resource and Operation LWM2M Resource or Resource Instance Child Content Sharing Resource
Write	create child Content Sharing Resource for new Resource or Resource Instance. The name of the Content Sharing Resource shall be the Resource Id for a singleton LWM2M Resource. The name of the Content Sharing Resource shall be the LWM2M Resource ID and LWM2M Resource Instance Id. When the LWM2M Resource is of type LWM2M Object Link, the <contentInstance> resource that represents the LWM2M Resource is used to represent the LWM2M Object Link by assigning the destination of of the LWM2M Object Link reference to another LWM2M Object's Content Sharing Resource. The reference is assigned using the <contentInstance> resource's contentRef attribute where the name of the attribute is "ObjectLink" and the value of the attribute is the URI of the destination <contentInstance> resource.
Not applicable	update Content Sharing Resource
Write	delete Content Sharing Resource for Resource or Resource Instance
Not Applicable	read Content Sharing Resource

Table 8.2.2-2: LWM2M Resource <contentInstance> Lifecycle Translation

LWM2M Operation Device Management & Service Enablement Interface	oneM2M Resource and Operation LWM2M Resource or Resource Instance <contentInstance> resource
Write	create <contentInstance>
Write - Sets the Resource to default value	delete <contentInstance>
Read	read <contentInstance>

8.2.3 Mapping for the Encoding of the <contentInstance> Resource

When an AE accesses a <contentInstance> resource, the AE needs to know how the value of the Resource or Resource Instance is encoded.

Table 8.2.3-1: Mapping of Resource or Resource Instance Encoding

Interworking Function Mapping	oneM2M Resource Attribute
The encoding of the LWM2M Resource or Resource Instance based on the Content-Type option	<contentInstance>: contentInfo. Possible contentInfo values are translated from the LWM2M Content-Type option. Note: The LWM2M Technical Specification [3] defines the value to be used for the [encoding] if the Content-Type option is not present.