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Re: A question for RDF parser implementers - whitespace

From: Norman Walsh <Norman.Walsh@Sun.COM>
Date: Fri, 09 Jul 2004 07:42:48 -0400
To: www-rdf-interest@w3.org
Message-ID: <87smc1csp3.fsf@nwalsh.com>
/ Graham Klyne <gk@ninebynine.org> was heard to say:
| I've just noticed something the the RDF syntax which has me wondering
| how RDF parser implementers are dealing with whitespace in literals.

Goldfarb's Law: If there's a problem in a text processing system, it
involves whitespace.

| The RDF syntax spec
| (http://www.w3.org/TR/rdf-syntax-grammar/#section-Nodes), section
| 6.1.9 on typed literals, mentions "In XML Schema (part 1)
| [XML-SCHEMA1], white space normalization occurs during validation
| according to the value of the whiteSpace facet. The syntax mapping
| used in this document occurs after this, so the whiteSpace facet
| formally has no further effect."

Fair enough. The RDF spec is using the schema-normalized-value of
typed literals.

| But, given that RDF/XML an open-ended tag set, schema validation of
| RDF/XML doesn't make a lot of sense.

Well, I'm not sure that follows. If you invent an RDF/XML vocabulary,
you could write a W3C XML Schema for it.

| Further, I don't have an XML
| schema processor to do such validation.

Ah, well, that's a different issue :-)

| How are other implementers dealing with this?  My inclination is to
| pass the original literal, with whitespace intact, and allow the
| subsequent datatype processing to treat it with the same effect as if
| the whiteSpace had been eliminated by schema validation.  For this
| purpose, the whitespace facet is implicitly part of the datatype.
|
| Does anyone have any other ideas on this?

I think if you are parsing a typed literal and you know you're parsing
a typed literal, you should collapse the whitespace before passing the
value on to down-stream applications.

Given that the RDF spec says that whitespace is eliminated by
validation, I can easily imagine writing an application that assumes
typed values like integers and URIs won't have insignificant
whitespace around them.

                                        Be seeing you,
                                          norm

-- 
Norman.Walsh@Sun.COM / XML Standards Architect / Sun Microsystems, Inc.
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Received on Friday, 9 July 2004 07:57:05 UTC

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