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Re: IRI guidance

From: Pierre-Antoine Champin <pierre-antoine.champin@liris.cnrs.fr>
Date: Fri, 29 Apr 2011 14:42:04 +0100
Message-ID: <4DBAC02C.3010707@liris.cnrs.fr>
To: Ivan Herman <ivan@w3.org>
CC: Eric Prud'hommeaux <eric@w3.org>, Alex Hall <alexhall@revelytix.com>, Nathan Rixham <nathan@webr3.org>, RDF WG <public-rdf-wg@w3.org>, Dan Brickley <danbri@danbri.org>
On 04/29/2011 02:29 PM, Ivan Herman wrote:
> 
> On Apr 29, 2011, at 15:17 , Pierre-Antoine Champin wrote:
> <snip/>
>>>>
>>>> [[
>>>> Note: RFC2397's mapping of IRIs to URIs does not alter "%25" or
>>>> punycoded domain names, which means that the IRIs
>>>> <http://伝言.example/R&D> and <http://xn--9oqp94l.example/R%25D> will
>>>> both be transformed to the URI to <http://xn--9oqp94l.example/R%25D>.
>>>> RFC2397 section 3.2. "Converting URIs to IRIs" defines a function
>>>> which produces a single IRI for any URI. When minting IRIs for RDF,
>>>> it is encouraged to mint forms which can round trip to a URI form
>>>> and back.
>>>> ]]
>>>
>>> I think that the round-trip issue may not be clear (it is not 100% clear to me either:-). 
>>
>> I, on the other hand, think the round-trip is a nice way to put it, and
>> quite well defined (although, see my concern #1 below).
>> An example of which IRI is produced from the URI above would help, though.
>>
> 
> My understanding is that, concentrating on the IDN case, the
> IRI->punycode does not work in 100% cases, although the punycode->IRI
> does. So round-trip would then mean using the punycode.

This is also my reading of RFC3987. Hence my concern #2 below.

> Is this what we want?

I would sure prefer <http://伝言.example/R&D> to be the encouraged URI
rather than <http://xn--9oqp94l.example/R&D> .

  pa


> 
> Ivan
> 
> 
> 
>>> Why not adding something like
>>>
>>> 'In other words, the use of %-escaped characters or punycode encoded IDN-s are strongly discouraged.'
>>
>> It definitely would not hurt.
>>
>> I have three concerns, though:
>>
>> 1/ from what I read in RFC3987, section 3.2, the mapping from URI to IRI
>> is not completely specified (refering to section 6.1 of that same RFC)
>>
>> 2/ the URI-to-IRI described in section 3.2 does not eliminate punycode.
>> So <http://伝言.example/R&D> is *not* round-trip-safe, but
>> <http://xn--9oqp94l.example/R&D> is.
>>
>> 3/ it should be made very clear that this is about minting IRIs from
>> scratch or from URIs, but *not* about converting IRIs (as IRIs that
>> would convert to the same URI are not consider equivalent).
>>
>>  pa
>>
>>
>>>
>>> Ivan
>>>
>>>
>>>
>>>>
>>>>
>>>>> Cheers
>>>>>
>>>>> Ivan
>>>>>
>>>>>
>>>>>>
>>>>>>
>>>>>>> -Alex
>>>>>>
>>>>>> -- 
>>>>>> -ericP
>>>>>>
>>>>>
>>>>>
>>>>> ----
>>>>> Ivan Herman, W3C Semantic Web Activity Lead
>>>>> Home: http://www.w3.org/People/Ivan/
>>>>> mobile: +31-641044153
>>>>> PGP Key: http://www.ivan-herman.net/pgpkey.html
>>>>> FOAF: http://www.ivan-herman.net/foaf.rdf
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>> -- 
>>>> -ericP
>>>
>>>
>>> ----
>>> Ivan Herman, W3C Semantic Web Activity Lead
>>> Home: http://www.w3.org/People/Ivan/
>>> mobile: +31-641044153
>>> PGP Key: http://www.ivan-herman.net/pgpkey.html
>>> FOAF: http://www.ivan-herman.net/foaf.rdf
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
> 
> 
> ----
> Ivan Herman, W3C Semantic Web Activity Lead
> Home: http://www.w3.org/People/Ivan/
> mobile: +31-641044153
> PGP Key: http://www.ivan-herman.net/pgpkey.html
> FOAF: http://www.ivan-herman.net/foaf.rdf
> 
> 
> 
> 
> 
Received on Friday, 29 April 2011 13:42:34 GMT

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