W3C home > Mailing lists > Public > public-rdf-dawg@w3.org > July to September 2005

Re: BASE IRI resolution: syntax-based normalization and/or scheme-based normalization?

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Mon, 25 Jul 2005 12:35:25 +0100
Message-ID: <42E4CE7D.4040902@hp.com>
To: Dan Connolly <connolly@w3.org>
CC: RDF Data Access Working Group <public-rdf-dawg@w3.org>



Dan Connolly wrote:
> A commentor points out in
> http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2005Jul/0042.html
> 
> that we're not explicit about whether section
> 6.2.2. "Syntax-Based Normalization" and/or
> 6.2.3. "Scheme-Based Normalization" of
> http://www.ietf.org/rfc/rfc3986.txt are applied
> to base IRIs in SPARQL. Consider this
> input data:
> 
>   @prefix : <http://example/vocab#>.
> 
>   :s1 :p <example://a/b/c/%7Bfoo%7D#xyz>.
>   :s2 :p <eXAMPLE://a/./b/../b/%63/%7bfoo%7d#xyz>.
> 
> and this query:
> 
>   PREFIX : <http://example/vocab#>
>   PREFIX p1: <eXAMPLE://a/./b/../b/%63/%7bfoo%7d#>
> 
>   SELECT ?S WHERE { ?S :p p1:xyz }
> 
> It seems to me that the simplest answer is that no,
> nothing gets canonicalized, and the answer is that
> ?S binds to :s2 only.
> 
> Then re scheme-based normalization, here's another test:
> 
>   @prefix : <http://example/vocab#>.
>   :s3 :p <http://example.com:80/#abc>.
>   :s4 :p <http://example.com/#abc>.
>   :s5 :p <http://example.com/#abc>.
> 
> query:
>   PREFIX : <http://example/vocab#>
>   PREFIX p2: <http://example.com:80/#>
> 
>   SELECT ?S WHERE { ?S :p p2:abc }
> 
> Let's see what current DawgShows say...
> SPARQLer ( http://sparql.org/query.html ) binds to
> s2 only in the 1st case and to s3 only in the 2nd case.

Yes, that's what I'd expect - SPARQLer will not apply scheme syntax or specific 
based normalization.

Checking the RDF recs (which predate RFC 3896)

http://www.w3.org/TR/rdf-concepts/#section-Graph-URIref
says:
"""
Two RDF URI references are equal if and only if they compare as equal, character 
by character, as Unicode strings.
"""

> 
> Likewise the rasqal demo
> http://librdf.org/query?language=sparql
> 
> 
> So I suggest adding those two tests to the test suites,
> and clarifying the spec: after
> 
> 
>  They stand for IRIs, either directly, or relative to a base IRI.
> 
> we add
> 
>  Relative IRIs are combined with base IRIs as per section
>  6.5.  Relative IRI References of [19], using only the
>  basic algorithm in section 5.  Reference Resolution
>  of [rfc3986], without the optional Syntax-Based Normalization
>  nor Scheme-Based Normalization.

Agreed.  I suggest adding a link to RDF concepts as well.

	Andy
Received on Monday, 25 July 2005 11:36:02 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:15:23 GMT