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Re: Absolute IRIs (Was: Re: IRI guidance)

From: Nathan <nathan@webr3.org>
Date: Mon, 02 May 2011 19:32:54 +0100
Message-ID: <4DBEF8D6.9040608@webr3.org>
To: Eric Prud'hommeaux <eric@w3.org>
CC: Ivan Herman <ivan@w3.org>, Alex Hall <alexhall@revelytix.com>, RDF WG <public-rdf-wg@w3.org>
Eric Prud'hommeaux wrote:
> * Ivan Herman <ivan@w3.org> [2011-05-02 19:39+0200]
>> On May 2, 2011, at 19:27 , Eric Prud'hommeaux wrote:
>>
>>> * Alex Hall <alexhall@revelytix.com> [2011-05-02 11:44-0400]
>>>> On Fri, Apr 29, 2011 at 2:28 PM, Ivan Herman <ivan@w3.org> wrote:
>>>>
>>>>>
>>>>> On 29 Apr 2011, at 19:50, Eric Prud'hommeaux <eric@w3.org> wrote:
>>>>>> I'm not personally keen on this absolute IRI restriction. I included
>>>>>> it in this proposal in order to minimize the permutations being
>>>>>> examined at once ("minimal change"). For usability, I find
>>>>>> Data:
>>>>>>   <s> <p> <o> .
>>>>>> Query:
>>>>>>   ASK { ?s <p> ?o }
>>>>>>
>>>>>> very intuitive when you don't have to specifically call out a base
>>>>>> URI. Using IRI references instead of IRIs would permit the above query
>>>>>> to work in e.g. Jena (which currently presumes absolute IRIs).
>>>>>>
>>>> Is there a need for this outside the context of illustrating some simple
>>>> test data and queries?
>>> It's really just a minor usability/simplicity point. The Direct
>>> Mapping of Relational Data to RDF maps a relational database to an RDF
>>> graph with all relative IRIs. Custodians of the data can treat it as
>>> they would a tarball of HTML docs in a filesystem, where the access,
>>> be it e.g. HTTP backed by some Apache configuration, or directly via
>>> file://localhost IRIs, determines the base. Like the browser's ability
>>> to navigate relative links, SPARQL queries can elide the base,
>>> matching RDF graphs regardless of access. When it doesn't work, I'd
>>> say it's a usability obstacle a little worse than issue 18 .
>> But, at this moment, we are discussing RDF concepts and not a particular serialization. One can use relative URI-s with @base in turtle, or the equivalents in other serializations. But I do not see how the introduction of relative URI-s into the RDF Concepts, Semantics, etc, could be a minor point...
> 
> Some implementors interpret the last URI references note in RDF Concepts as saying that they are not allowed to put relative IRIs into an RDF graph. My question is, does the world get better or worse if we leave that note out. I've found RDF pipeline processing (constructs, queries, service federation, etc.) to be handy with relative IRIs, but we don't want persistent aggregators (e.g. an RDF Google) to be polluted with lots of ambiguous relative IRIs.

I'm missing something here, the value space is IRIs yes, but regardless 
of where you're working you always deal with some form of lexical space 
(serialization, memory structure, rdbms) - is there any limitation 
anywhere that says you can't store / represent an IRI as a relative 
reference rather than an absolute value? Surely that's behind the public 
interface and in the realm where anybody can do whatever they want.

Best,

Nathan
Received on Monday, 2 May 2011 18:33:50 GMT

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