Subject: [core] Does one have to use registered resource type (rt) values?

From: Christer Holmberg <[email-masked]>
Date: Tue, 15 Oct 2019 08:11:09 +0000

Hi,

There is an IANA registry for resource type (rt) values.

QUESTION: Does one have to use registered rt values, or can one use non-registered values? Section 3.1 of RFC 6690 does mention the registry. But, the text also talks values with “application-specific semantics”, which suggests that one could use non-registered values.

IRFC 6690 also use both “temperature-c” and “light-lux”, but none of them are registered. I DO realize these are just example values, which would justify the fact that they are not registered. But it adds to the confusion whether registration is required.

Regards,

Christer

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From: Christian Amsüss <[email-masked]>
Date: Tue, 15 Oct 2019 14:58:08 +0200

Hello Christer, hello CoRE group,

On Tue, Oct 15, 2019 at 08:11:09AM +0000, Christer Holmberg wrote:
> QUESTION: Does one have to use registered rt values, or can one use
> non-registered values? Section 3.1 of RFC 6690 does mention the
> registry. But, the text also talks values with “application-specific
> semantics”, which suggests that one could use non-registered values.

My understanding is that the options for those applications are to

* provide a specification and enter the value into the registry, or to 
* use URIs for rt values, as they do not need to be registered.

OIC, OMA and Fairhair registered resource types as part of quite large
specifications. There is no need for that that much text, though: A
concise definition of what the resource type means would probably be
enough, and there are no requirements on the organizational background
of the registrant.

I have not seen URIs in use in combination with link-format out in the
wild, and (given their verbosity) don't really expect them to before
CoRAL comes into active use.

> IRFC 6690 also use both “temperature-c” and “light-lux”, but none of
> them are registered. I DO realize these are just example values, which
> would justify the fact that they are not registered. But it adds to
> the confusion whether registration is required.

Yes, that is a problem that has come up in other documents as well.

Would it help to have example values registered that can then be used in
other examples, possibly using the previously discussed hierarchical
allocation and claiming the `example.*` space for that? (Or to not
register them, but at least prefix examples?)

Best regards
Christian

-- 
This may seem a bit weird, but that's okay, because it is weird.
  -- perldata(1) about perl variables

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From: Christer Holmberg <[email-masked]>
Date: Tue, 15 Oct 2019 13:27:51 +0000

Hi,
    
>    register them, but at least prefix examples?)

People often use terms like "foo" and "bar", and those are not registered, so I am not sure whether registration is needed. Having said that, if we want to point out that a link e.g., is related with a temperature sensor, using "temperature" instead of "foo" is much better.

Prefix could be a good option, and then there could be a generic statement somewhere saying that such values are only used for example purpose, and must not be used in real deployments.

Regards,

Christer