W3C home > Mailing lists > Public > public-rdfa-wg@w3.org > April 2013

@lang and @datatype interaction

From: Reece Dunn <msclrhd@googlemail.com>
Date: Wed, 17 Apr 2013 13:13:34 +0100
Message-ID: <CAGdtn27oR9fs_HipieMKAX+cD8GE7yJqaXYAE4Yg853sdmeWRA@mail.gmail.com>
To: RDFa WG <public-rdfa-wg@w3.org>
Hi,

I am adding RDFa-based metadata to my website and have observed different
behaviour in RDFa processors with @lang and @datatype interaction.

I have created two test cases:

cat > testcase1.html < EOF
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" prefix="dct:
http://purl.org/dc/terms/ xsd: http://www.w3.org/2001/XMLSchema# s:
http://schema.org/">
 <head>
  <title>Test Case</title>
 </head>
 <body about="http://example.org/foo">
  <p property="dct:date" datatype="xsd:string" content="2010-11-12">2010</p>
 </body>
</html>
EOF

and:

cat > testcase2.html < EOF
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" prefix="dct:
http://purl.org/dc/terms/ xsd: http://www.w3.org/2001/XMLSchema# s:
http://schema.org/">
 <head>
  <title>Test Case</title>
 </head>
 <body about="http://example.org/foo">
  <p property="dct:date" datatype="xsd:string" content="2010-11-12">2010</p>
 </body>
</html>
EOF

The difference is that testcase2.html specifies an @lang attribute in the
root html node.

NOTE: The xmlns="http://www.w3.org/1999/xhtml" is to work around a segfault
in the version of rapper I am using (fixed in the latest release).

Running `rapper -i rdfa -o turtle testcase1.html` and `rapper -i rdfa -o
turtle testcase2.html` I get:
-----
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix : <http://www.w3.org/1999/xhtml> .

<http://example.org/foo>
    <http://purl.org/dc/terms/date> "2010-11-12"^^<
http://www.w3.org/2001/XMLSchema#string> .
-----

Using RDF::RDFa:
-----
require 'rdf/rdfxml'
require 'rdf/rdfa'
require 'rdf/turtle'

prefixes = {}
graph1 = RDF::Graph.load("testcase1.html", :prefixes => prefixes)
graph2 = RDF::Graph.load("testcase2.html", :prefixes => prefixes)

puts graph1.dump(:turtle, :prefixes => prefixes)
puts '==='
puts graph1.dump(:rdfxml, :prefixes => prefixes)
puts '==='
puts graph2.dump(:turtle, :prefixes => prefixes)
puts '==='
puts graph2.dump(:rdfxml, :prefixes => prefixes)
-----

I get:
-----
@prefix dct: <http://purl.org/dc/terms/> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<http://example.org/foo> dct:date "2010-11-12"^^xsd:string .
===
<?xml version="1.0" encoding="UTF-8"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dct="
http://purl.org/dc/terms/">
  <rdf:Description rdf:about="http://example.org/foo">
    <dct:date rdf:datatype="http://www.w3.org/2001/XMLSchema#string
">2010-11-12</dct:date>
  </rdf:Description>
</rdf:RDF>
===
@prefix dct: <http://purl.org/dc/terms/> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<http://example.org/foo> dct:date "2010-11-12"@en^^xsd:string .
===
<?xml version="1.0" encoding="UTF-8"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dct="
http://purl.org/dc/terms/">
  <rdf:Description rdf:about="http://example.org/foo">
    <dct:date xml:lang="en">2010-11-12</dct:date>
  </rdf:Description>
</rdf:RDF>
-----

Here, the turtle serialisation is wrong (a literal cannot have both a
language and a datatype specifier) and the RDF/XML serialisation is using
the language instead of the datatype. It looks like the RDFa processor is
incorrectly including both a language and datatype.

Is it possible to add these test cases to the EARL tests?

What is the correct behaviour in this case? I am expecting @datatype to
override @lang as the rapper tool is doing.

Thanks,
- Reece
Received on Wednesday, 17 April 2013 12:14:02 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 17:05:34 UTC