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[closed] Re: N-Triples VS RDF/XML bNode identifiers

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Thu, 30 Oct 2003 10:37:00 +0000
To: Arjohn Kampman <arjohn.kampman@aduna.biz>
Cc: www-rdf-comments@w3.org
Message-Id: <20031030103700.1135beff.dave.beckett@bristol.ac.uk>

On Tue, 28 Oct 2003 10:15:42 +0100, Arjohn Kampman <arjohn.kampman@aduna.biz> wrote:

> 
> Dear editors of the RDF Test Cases document,
> 
> Last week, we stumbled across a problem in Sesame when RDF was read from
> an RDF/XML document and then written as N-Triples. The problem was
> related to the bNode identifiers, whose definition in RDF/XML and
> N-Triples is slightly different:
> 
> While parsing the RDF/XML, the parser generated bNode IDs that were
> legal according to the RDF/XML specs and these were written as-is to the
> N-Triples document. An example bNode identifier is "node09FC-1E4A-2". In
> RDF/XML, the dashes (and underscores, etc.) are legal characters for
> bNode identifiers. In N-Triples, however, only (ASCII-)letters and
> number can be used. Thus the procedure sketched out above resulted in an
> illegal N-Triples document.
> 
> So, my question is: wouldn't it be convenient to make the two
> definitions identical?

It might be convienient but sadly, I don't think it's realistic.

An rdf:nodeID in RDF/XML defined at
  http://www.w3.org/TR/rdf-syntax-grammar/#nodeIdAttr
takes as a value a string compatible with an XML name:
  http://www.w3.org/TR/rdf-syntax-grammar/#rdf-id
which has a wide range of characters allowed and
permits the full range of international characters.

It is also useful to re-use this XML definition since it enables checking
using the standard XML NCName term (which can be then checked
by XML schema languages which likely support that)

The subset that are also legal as N-Triples is thus rather narrow.

N-Triples also has had a (weak, but remains, "would be-nice")
requirement to keep itself as a subset of N3.  N3 imposes several
restrictions on the names that are allowed, and they vary between
implementations.  The current set of allowed names define dby
  http://www.w3.org/TR/rdf-testcases/#name
is thus not likely to change.  

I think '-' in particular might have other uses in N3 for paths,
arithmetic, a funky -_ encoding scheme or may be reserved or unwise.
You'd have to ask the N3 developers, since I can't recall all the details.

Please reply, copying www-rdf-comments@w3.org whether this response
is an acceptable disposition of your comment.

Thanks

Dave
Received on Thursday, 30 October 2003 05:38:45 GMT

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