Live Objects - complete developer guide

DeviceTwin

LiveObjects DeviceTwin is a Twin representation of the real device:

which objects are supported
which objects are instantiated
which are the instantiated objects last reported attributes values

Figure 1. DeviceTwin overview

A DeviceTwin includes :

supportedObjects as a list of objectDefinitionId : list Object definitions supported by the device.
instantiatedObjects as a list of Object : list of Object implemented by the device.
reportedValues as a list of AttributeValue : list of Attributes values reported by the device

In addition, LiveObjects provides three ways to represents a given DeviceTwin :

By RootObject.
By Object.
By ObjectInstance.

RootObject

RootObject is represented by the following :

Field	Value	Comment
objectDefinitionId	urn:oma:lwm2m	Parent of the ObjectDefinition identifier.
path	/	Root path
children	[]	Children Object

Field

Value

Comment

objectDefinitionId

urn:oma:lwm2m

Parent of the ObjectDefinition identifier.

path

Root path

children

[]

Children Object

Object

Object is represented by the following :

Field Value Comment

Field	Value	Comment
objectDefinitionId	urn:oma:lwm2m:5:1.1	ObjectDefinition identifier.
path	/5	Object path : object (OBJECT_MAP) `5`
instances	[]	List of ObjectInstance

objectDefinitionId

urn:oma:lwm2m:5:1.1

ObjectDefinition identifier.

path

Object path : object (OBJECT_MAP) 5

instances

[]

List of ObjectInstance

ObjectInstance

ObjectInstance is represented by the following :

Field Value Comment

Field	Value	Comment
objectDefinitionId	urn:oma:lwm2m:5:1.1	ObjectDefinition identifier.
path	/5/0	Object path : object (OBJECT_MAP) `5` instance `0`
attributes	[]	List of Attribute

objectDefinitionId

urn:oma:lwm2m:5:1.1

ObjectDefinition identifier.

path

/5/0

Object path : object (OBJECT_MAP) 5 instance 0

attributes

[]

List of Attribute

Attribute

Attribute is represented by the following :

Field Value Comment

Field	Value	Comment
path	`/5/0/3`	Attribute path : object `5` instance `0` attribute `3`. A root Object has an empty path.
`/1/4/25/0`	Attribute path : object `1` instance `4` multi-instances attribute `25` instance `0`.
content	`AttributeValue`	Single instance attribute
contents	`List<AttributeValue>`	Multi-instances attributes

path

/5/0/3

Attribute path : object 5 instance 0 attribute 3. A root Object has an empty path.

/1/4/25/0

Attribute path : object 1 instance 4 multi-instances attribute 25 instance 0.

content

AttributeValue

Single instance attribute

contents

List<AttributeValue>

Multi-instances attributes

When an attribute is a single-instance attribute, his value is reported as content, whereas a multi-instances attribute is reported as contents.