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

From: Ivan Herman <ivan@w3.org>
Date: Mon, 2 May 2011 19:39:27 +0200
Cc: Alex Hall <alexhall@revelytix.com>, "nathan@webr3.org" <nathan@webr3.org>, RDF WG <public-rdf-wg@w3.org>
Message-Id: <9913ECD2-F07D-4FC7-9EE7-FDA8596851B8@w3.org>
To: Eric Prud'hommeaux <eric@w3.org>

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...

Ivan



> 
> 
>>> Do you mean that the RDF concepts should allow relative URI-s (well, IRI-s)
>>> in Graphs? That might be a pretty major change in RDF; what would
>>> dereferencing mean? Where would the base come from? Would two graphs with
>>> different bases but otherwise identical relative IRI-s be identical? Etc...
>>> 
>>> Do we have a convincing use case to engage into this?
>>> 
>> 
>> I agree -- allowing relative IRIs in the abstract syntax is a potentially
>> far-reaching change which I am personally opposed to.  I think it's worth
>> sacrificing a little bit of convenience on the part of a document author in
>> order to gain the consistency that absolute IRIs provide in terms of
>> preserving the meaning of a graph.
>> 
>> -Alex
>> 
>> 
>> 
>>> 
>>> Ivan
> 
> -- 
> -ericP
> 


----
Ivan Herman, W3C Semantic Web Activity Lead
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Received on Monday, 2 May 2011 17:38:14 GMT

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