W3C home > Mailing lists > Public > public-rdf-wg@w3.org > May 2011

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

From: Eric Prud'hommeaux <eric@w3.org>
Date: Mon, 2 May 2011 14:13:24 -0400
To: Ivan Herman <ivan@w3.org>
Cc: Alex Hall <alexhall@revelytix.com>, "nathan@webr3.org" <nathan@webr3.org>, RDF WG <public-rdf-wg@w3.org>
Message-ID: <20110502181323.GB29704@w3.org>
* 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.


> 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
> 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
Received on Monday, 2 May 2011 18:13:55 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:25:42 GMT