[core] Re: Coreconf Notifications

[Alex Huang Feng <[e-mail]>]

Dear Carsten,

My apologies, checking again, you are right, tags are needed for RFC9254.

What I want to raise (and discuss) in this thread is NOT how the datetime specified in the leaf “eventTime” is encoded in CBOR.
I agree with Carsten that draft-bormann-cbor-yang-standin-00 can be used in draft-ahuang-netconf-notif-yang for better encoding the datetime.

As I said on the mic during the WG meeting, there is a gap on how YANG notifications are currently encoded in the different YANG encodings (XML, JSON, CBOR).
Having a common structure for such notifications is beneficial to YANG tooling (such as the integration of YANG into the Kafka Schema registry https://github.com/network-analytics/draft-daisy-kafka-yang-integration/blob/main/schema-registry-yangkit-integration-03.pdf)

What I am referring to as a structure is the metadata that needs to be present in the notification header.
The current understanding at NETCONF WG is that the notification header MUST have a eventTime leaf, as specified in RFC5277.
RFC5277 was dedicated to XML, but YANG notifications have been generalised with YANG-Push [RFC8641].

The current understanding is that in XML, a notification is encoded as follows:

<notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
    <eventTime>2007-07-08T00:04:00Z</eventTime>       <— eventTime present
    <event xmlns="http://example.com/event/1.0">
        <eventClass>fault</eventClass>
        <reportingEntity>
            <card>ATM1</card>
        </reportingEntity>
        <severity>minor</severity>
    </event>
</notification>

JSON as:

{
    "ietf-notification:notification": {
        "eventTime": "2023-02-10T08:00:11.22Z”,     <—eventTime present
        "yang-defining-notif:event": {
            "eventClass": "fault",
            "reportingEntity": {
                "card": "ATM1"
            },
            "severity": "minor"
        }
    }
}

And CBOR (diag-notation) I would expect:
{
    "ietf-notification:notification": {
        "eventTime": "2023-02-10T08:00:11.22Z”,    <— eventTime present
        "yang-defining-notif:event": {
            "eventClass": "fault",
            "reportingEntity": {
                "card": "ATM1"
            },
            "severity": "minor"
        }
    }
}

That is what we are trying to solve with https://datatracker.ietf.org/doc/html/draft-ahuang-netconf-notif-yang-05; having a common schema for all the YANG notifications and having a YANG module defining such structure.

That is why I was suggesting to the authors of draft-ietf-core-comi-18 to use this draft as reference rather than RFC5277 (as Thomas Graf was saying, RFC5277 is expected to be obsoleted)

On a second note, I’d be happy to hear any feedback from the CORE WG whether updating RFC9254 is the way to go to solve this issue with CBOR notifications in https://datatracker.ietf.org/doc/html/draft-ahuang-netconf-notif-yang-05.

Cheers,
Alex

> On 20 Jul 2024, at 08:42, Carsten Bormann <[e-mail]> wrote:
> 
> Hi Alex
> 
> On 2024-07-20, at 00:37, Alex Huang Feng <[e-mail]> wrote:
>> 
>> Thanks for the pointers, will check out this draft. My text does not state that the timestamp needs to be encoded as text-encoded date-time.
> 
> I would expect that you would want to encode these using standard YANG means, and (without YANG-CBOR with stand-in tags) that would be the RFC 3339 date-times used in RFC 6991.
> (Which resolution do you need in practice for eventtime, by the way?)
> 
> 
>> Are you suggesting that the draft should state the usage of tags for date-times? For implementations that does not support tags, isn’t it contra-productive?
> 
> You cannot do YANG-CBOR without CBOR tags, so I don’t think there is an actual problem.
> 
> By the way, you may want to look at the CoRE telemetry spec [1].
> This is six years old (we just didn’t have the RFCs in place for YANG-CBOR and YANG SID at the time, so the draft was a bit premature), but it solves many of the problems being discussed right now.
> (Henk will be at the Hackathon, so please talk to him about that.)
> 
> Grüße, Carsten
> 
> [1]: https://datatracker.ietf.org/doc/html/draft-birkholz-yang-core-telemetry-01
>