Re: [netmod] XML and prefix

[Ladislav Lhotka <[e-mail]>]

On 14. 01. 22 12:23, Martin Björklund wrote:
> Hi,
> 
> Ok, I think I understand what he means.  With this XML:
> 
>    <alarm-category xmlns:nsfmi="urn:ietf:params:xml:ns:yang\
>                                :ietf-i2nsf-nsf-monitoring">
>        nsfmi:memory-alarm
>    </alarm-category>
> 
> the prefix "nsfmi" is present in the element data, which means that
> in order to implement this properly, the XML parser must pass the
> namespace mappings to the user code.
> 
> So he proposes to add to the draft:
> (from https://mailarchive.ietf.org/arch/msg/i2nsf/06kJ7vS6X-0hUmGHrCWN-jVzU7M)
> 
> 11.  XML Examples for I2NSF NSF Monitoring
> 
>     This section shows the XML examples of I2NSF NSF Monitoring data
>     delivered via Monitoring Interface from an NSF.  In order for the XML
>     to work, the prefix in the element that uses "identityref" type
>     (e.g., /i2nsf-event/i2nsf-system-detection-alarm/alarm-category/) in
>     the YANG module described in this document MUST be the same as the
>     namespace prefix for urn:ietf:params:xml:ns:yang:ietf-i2nsf-nsf-
>     monitoring.  The XML software MUST be chosen that makes the namespace
>     prefix information available.
> 
> 
> I think this is a bit odd.  Who is supposed to act on the first MUST?
> This text is about an example, which is what it is, and it happens to
> be correct.
> 
> Also, the text about XML software seems unnecessary to me.  It follows
> from the definition of an identityref in RFC 7950 that the namespace
> mapping is needed to parse this correctly.
> 

This is not unique to YANG. For example, XSLT and RELAX NG use XML 
prefixes in the values of XML attributes.

Lada

> 
> /martin
> 
> 
> 
> 
> 
> Ladislav Lhotka <[e-mail]> wrote:
>> On 14. 01. 22 11:39, Martin Björklund wrote:
>>> Hi,
>>> I don't understand the problem either.  He writes:
>>>
>>>> Sorry, but this has the same problem in figure 11.1 that we've just
>>>> been
>>>> discussing with Ian.
>>> Can you send a pointer to that discussion?  Perhaps there's more
>>> context there.
>>
>> Right. I also suspect that the last sentence should have been
>>
>> "I don't think it's OK for the draft to say those things."
>>
>> Lada
>>
>>> /martin
>>> tom petch <[e-mail]> wrote:
>>>> I see that IANA have taken to asking XML Registry experts about the
>>>> registration of YANG namespaces at Last Call, or perhaps they have
>>>> always done this but have only recently put the e-mail on a public
>>>> list.  Anyhow, the experts have taken it upon themselves to comment on
>>>> the XML examples and I do not understand this comment.  This comes
>>>> from
>>>> [IANA #1217705] Expert Review for
>>>> draft-ietf-i2nsf-nsf-monitoring-data-model-12 (xml-registry)
>>>> by Tim Bray 17 dec 2021 03:03
>>>>
>>>> ===============================
>>>> Sorry, but this has the same problem in figure 11.1 that we've just
>>>> been
>>>> discussing with Ian.
>>>>
>>>> For it to work, (a) the prefix in the alarm-category element MUST be
>>>> the
>>>> same as the namespace prefix for
>>>> urn:ietf:params:xml:ns:yang:ietf-i2nsf-nsf-monitoring, which means
>>>> that XML
>>>> software MUST be chosen that makes the namespace prefix information
>>>> available.  I don't think it's OK for the draft not to say those
>>>> thigns.
>>>>
>>>> <alarm-category
>>>>              xmlns:nsfmi="urn:ietf:params:xml:ns:yang:\
>>>>                         ietf-i2nsf-nsf-monitoring">
>>>>              nsfmi:memory-alarm
>>>>            </alarm-category>
>>>> =================================================
>>>> a) I am unclear what the problem is - I thought that XML allowed great
>>>> freedom with prefix even if the IETF would rather not
>>>> b) this suggestion seems to be that all I-D with XML examples, which
>>>> is pretty much every I-D with a YANG module in it, needs to carry a
>>>> warning about what XML software to choose, which seems rather a
>>>> burden.  Thoughts?
>>>>
>>>> Tom Petch
>>>>
>>>>
>>>>
>>>>
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>>
>> -- 
>> Ladislav Lhotka
>> Head, CZ.NIC Labs
>> PGP Key ID: 0xB8F92B08A9F76C67

-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67