Lwm2m CBOR format - specify Create operation payload about oma_lwm2m_for_developers HOT 2 CLOSED

Hi,

We also spotted the ambiguity and in the next release of the LwM2M TS, the related text is updated to:

According to the ABNF syntax above, the values are encoded in a CBOR map (Major type 5). The key of the data items is the ID of the underlying Object, Object Instance, Resource, or Resource Instance. Except when used for a Write or Create operation, The IDs inside the top-level payload MUST start with the Object ID.

In the LwM2M CBOR payload of the "Create" operation, MAX_ID 65535 MAY be used to indicate there is no reference to an Object Instance.

We also added this example payloads:

Create Operation Example

A Create operation to the LwM2M ACL Object (Create /2) of the LwM2M example client could contain the following LwM2M CBOR payload. This example has a size of 17 bytes.

A1             # map(1)
   82          # array(2)
      02       # unsigned(2)
      05       # unsigned(5)
   A4          # map(4)
      00       # unsigned(0)
      05       # unsigned(5)
      01       # unsigned(1)
      00       # unsigned(0)
      82       # array(2)
         02    # unsigned(2)
         18 66 # unsigned(102)
      00       # unsigned(0)
      03       # unsigned(3)
      18 65    # unsigned(101)

The same example using the CBOR diagnostic notation is shown below.

{[2, 5]: {0: 5,
          1: 0,
          [2, 102]: 0,
          3: 101}}

In the example above, the LwM2M Server requests the creation of a new Object Instance with ID: 5. To let the LwM2M Client assign the ID of the created Object Instance, the LwM2M CBOR payload could be the following:

A1             # map(1)
   82          # array(2)
      02       # unsigned(2)
      19 FFFF  # unsigned(65535)
   A4          # map(4)
      00       # unsigned(0)
      05       # unsigned(5)
      01       # unsigned(1)
      00       # unsigned(0)
      82       # array(2)
         02    # unsigned(2)
         18 66 # unsigned(102)
      00       # unsigned(0)
      03       # unsigned(3)
      18 65    # unsigned(101)

The same example using the CBOR diagnostic notation is shown below.

{[2, 65535]: {0: 5,
              1: 0,
              [2, 102]: 0,
              3: 101}}

Regards,

from oma_lwm2m_for_developers.

The bugfix release of the LwM2M v1.2 specification will be published in Q4 2022, according to the plans of the OMA DMSE/IPSO working group and it will contain this fix.

from oma_lwm2m_for_developers.