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Re: URI Comparisons: RFC 2616 vs. RDF

From: Nathan <nathan@webr3.org>
Date: Thu, 20 Jan 2011 17:07:08 +0000
Message-ID: <4D386BBC.9090806@webr3.org>
To: Martin Hepp <martin.hepp@ebusiness-unibw.org>
CC: "public-lod@w3.org" <public-lod@W3.ORG>, David Booth <david@dbooth.org>, Dave Reynolds <dave.e.reynolds@gmail.com>
Martin Hepp wrote:
> On 20.01.2011, at 15:40, Nathan wrote:
>> David Booth wrote:
>>> On Thu, 2011-01-20 at 13:08 +0000, Dave Reynolds wrote:
>>> [ . . . ]
>>>>
>>>> To make sure that dereference returns what I expect, independent of
>>>> aliasing, then I should publish data with explicit base URIs (or just
>>>> absolute URIs). Publishing with relative URIs and no base is a recipe
>>>> for having your data look different from different places. Just 
>>>> don't do
>>>> it.
>>> This advice sounds like an excellent candidate for publication in a best
>>> practices document.  And if it is merely best practice guidance, perhaps
>>> that *is* something that the new RDF working group could address.
>>
>> +1 from me, address at the publishing phase, allow at the consuming 
>> phase, keep comparison simple.
> 
> I am not sure whether you are also talking of RDFa, but in case you do, 
> I would like to add the following:

Hi Martin,

Yes (re RDFa), see: http://webr3.org/urinorm/2 - all the browsers do the 
normalization so you can't even get to the non-normalized URI.

in a browser you'll note that all the URIs get normalized automatically, 
in that it's impossible to programmatically access the "correct" casing. 
That's a problem.

if you run it through the RDFa distiller at w3.org [2] you'll find:

   <htTp://WEBR3.org/urinorm/2> dc:creator <http://WEBR3.org/nathan#me> .

   <http://WEBR3.org/urinorm/2#example> dc:title "URI Normalization 
Example 2" .

note one of the URIs (the one which required relative path resolution) 
has the scheme normalised.

if you run if through check.rdfa.info you'll find that all the URIs are 
normalized. [3]

if you run it through sigma [4] you'll find everything has been 
normalized. You can also see an RDF view of this [5]

if you run it through URI Burner [6], you'll find that /some/ URIs have 
been normalized. It's also worth noting that this caused all kinds of 
problems - I ended up having to create a new resource at this point w/ 
some RDF & N3 to test URI Burner:

   http://webr3.org/urinorm/3

which lead to the empty [7] then I figured I'd try [8] and if you click 
the creator ( htTp://WEBR3.org/nathan#me ) since in this case there's no 
normalization (not it was normalized in [6]) you get a 400 Bad Request [9].

and so on and so forth - far from ideal.

Best,

Nathan

[1] http://www.rdfabout.com/demo/validator/ (normalizes all RDF URIs)
[2] http://www.w3.org/2007/08/pyRdfa/
[3] http://check.rdfa.info/check?url=http://webr3.org/urinorm/2&version=1.0
[4] http://sig.ma/search?q=http://webr3.org/urinorm/2
[5] http://sig.ma/entity/e6a2c8319bb3bf21f4b4639216f114a4.rdf#this
[6] 
http://linkeddata.uriburner.com/about/html/http/webr3.org/urinorm/2%01this
[7] http://linkeddata.uriburner.com/about/html/http/webr3.org/urinorm/3
[8] http://linkeddata.uriburner.com/about/html/htTp://WEBR3.org/urinorm/3
[9] http://linkeddata.uriburner.com/about/html/htTp/WEBR3.org/nathan%01me
Received on Thursday, 20 January 2011 17:10:50 UTC

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