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Re: IRI guidance

From: Pierre-Antoine Champin <pierre-antoine.champin@liris.cnrs.fr>
Date: Fri, 29 Apr 2011 14:17:53 +0100
Message-ID: <4DBABA81.7010704@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>
Hi,

I like Eric's proposal; though I think it requires
 s/RFC2397/RFC3987/g
applied to it...

On 04/29/2011 01:30 PM, Ivan Herman wrote:
> On Apr 29, 2011, at 14:14 , Eric Prud'hommeaux wrote:
<snip/>
>> I agree with Alex that punycoded domain names and %-escaped characters should be mentioned in the same breath. From a human-engineering perspective, I think any text specifying syntactic hints to help observers visually discriminate them discourages programmers from being conscientious about the distinction. However, if we want to encourage the world to mint IRIs which we can procedurally calculate from URIs (motivated perhaps by associating HTTP traffic with assertions about resources), we could add some text encouraging an unambiguous transformation:
>>
>> [[
>> 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.

> 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
> 
> 
> 
> 
> 
> 
Received on Friday, 29 April 2011 13:18:23 GMT

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