Subject: [core] Dynlink: pmin and pmax

From: David Navarro <[email-masked]>
Date: Fri, 9 Oct 2020 09:27:48 +0000

Hi,

I'm a member of the OMA LwM2M working group. The LwM2M protocol is using Minimum Period (pmin) and Maximum Period (pmax) attributes, among others.

Regarding these attributes, the DynLink draft has this requirement for pmax:
> The maximum period MUST be greater than zero and MUST be greater than the minimum period parameter (if present)

In its version 1.0, LwM2M had a different version of this requirement in the form:
> The maximum period parameter MUST be not smaller than the minimum period parameter.

Thus having pmax equal to pmin was allowed.

In LwM2M 1.1 we aligned this requirement with the DynLink one, making pmin equal to pmax forbidden.
However, it was brought to our attention[1] that having pmin equal pmax is a valid use case if the client wants the notification to be sent exactly every N seconds.

Is there a strong opinion on forbidding pmax to be equal to pmin, or are people open to changing the Dynlink requirement ?

I opened an issue for this: https://github.com/core-wg/dynlink/issues/25
And a matching pull request: https://github.com/core-wg/dynlink/pull/26

Best regards,
David Navarro

[1] https://github.com/OpenMobileAlliance/OMA_LwM2M_for_Developers/issues/495