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Re: IRI guidance

From: Ivan Herman <ivan@w3.org>
Date: Fri, 29 Apr 2011 15:53:21 +0200
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>
Message-Id: <9C4E7B72-01DA-4EB4-BC87-DFF44FE0E6D4@w3.org>
To: Pierre-Antoine Champin <pierre-antoine.champin@liris.cnrs.fr>

On Apr 29, 2011, at 15:42 , Pierre-Antoine Champin wrote:

> 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> .

Absolutely. But that means referring to round-tripping is _not_ what we want there!

Ivan


> 
>  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
>> 
>> 
>> 
>> 
>> 
> 


----
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 13:52:18 GMT

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