Interfaces

According to the architecture diagram [LWM2M-AD], there are four interfaces: 1) Bootstrap, 2) Client Registration, 3) Device Management and Service Enablement, and 4) Information Reporting. The operations for the four interfaces can be classified as uplink operations and downlink operations. The operations of each interface are defined in this section, and then mapped to protocol mechanisms in Section 8 Transport Layer Bindings and Encodings.

Figure 3 shows the operation model for interface “Bootstrap”. For this interface, the operations are uplink operation named “Request Bootstrap” and a downlink operation named “Write” and “Delete”. These operations are used to initialize the needed Object(s) for the LWM2M Client to register with one or more LWM2M Servers. Bootstrapping is also defined using Factory Bootstrap (e.g. storage in Flash) or Bootstrap from Smartcard (storage in a Smartcard).

Figure 3: Bootstrap

Figure 4 shows the operation model for the interface “Client Registration”. For this interface, the operations are uplink operations named “Registration”, “Update” and “De-register”.

Figure 4: Client Registration

Figure 5 shows the logical operation model for interface “Device Management and Service Enablement”. For this interface, the operations are downlink operations named “Read”, “Create”, “Delete”, “Write”, “Execute”, “Write Attributes”, and “Discover”. These operations are used to interact with the Resources, Resource Instances, Objects, Object Instances and/or their attributes exposed bythe LWM2M Client. The “Read” operation is used to read the current values; the “Discover” operation is used to discover attributes and to discover which Resources are implemented in a certain Object; the “Write” operation is used to update the values; the “Write Attributes” operation is used to change attribute values and the “Execute” operation is used to initiate an action. The “Create” and “Delete” operations are use to create or delete Instances.

Figure 5: Device Management and Service Enablement

Figure 6 shows the operation model for interface “Information Reporting”. For this interface, the operations are downlink operations “Observe” or “Cancel Observation” and an uplink operation “Notify”. This interface is used to send the LWM2M Server a new value related to a Resource on the LWM2M Client.

Figure 6: Information Reporting

The relationship between operations and interfaces is listed in the following Table 1.

Table 1: Relationship of operations and interfaces