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Re: last word on RDF serialization and QNames?

From: Jonathan Borden <jonathan@openhealth.org>
Date: Sun, 12 Oct 2003 16:03:23 -0400
Message-ID: <3F89B38B.6020706@openhealth.org>
To: Garret Wilson <garret@globalmentor.com>
Cc: www-rdf-interest@w3.org

Garret Wilson wrote:

>
> Everyone,
>
> What's the last word on RDF serialization and QNames---has this been 
> settled, and if so, what's the authoritative document? I've found 
> numerous discussions, but nothing definitive.

The last word is: "fribbet". This email is authoritative if you agree 
with what it says :-)

>
> The problem, as everyone probably knows, is that once an RDF+XML 
> document is processed, all qnames are collapsed into static URIs. 
> That's fine for RDF interpretation, but rough for re-serialization.

It depends on what you desire for "re-serialization". True, you cannot 
guarantee that all the namespaces and local names will end up exactly 
the same, but if you limit your desires to: *two RDF/XML documents that 
when parsed yield identical N-triples*, that is to say require:

1) an RDF/XML input document
2) parse to N-triples
3) reserialize to RDF/XML
4) parse to N-triples

you *can* develop an algorithm that will readily return equivalent 2) 
and 4) N-triples documents.

>
> I've read a document somewhere that describes how to guess at the 
> original namespace+localname serialization given a URI (does anyone 
> remember where to find this document?), but this doesn't work for some 
> combinations such as http://www.w3.org/1999/xlinkhref (which would 
> yield (http://www.w3.org/1999/, xlinkhref).

yeah it doesn't necessarily matter what the original namespace+localname 
*is*, does it? if so, you are currently SOL. That is to say:

<rdf:Description rdf:ID="baz" xmlns:foo="http://www.w3.org/1999/">
    <foo:bar>3</foo:bar>
</rdf:Description>

and

<rdf:Description rdf:ID="baz" xmlns:foob="http://www.w3.org/1999/b">
    <foob:ar>3</foob:ar>
</rdf:Description>

both yield the same triple:

<#baz> <http://www.w3.org/1999/bar> "3" .

Consequently an RDF application (an application which takes its 
semantics from the RDF Model Theory) shouldn't care less from which 
source document it got its triples.

> ...
>
> Is there anything authoritative on this?
>
You heard it here.

Jonathan
Received on Sunday, 12 October 2003 16:03:30 GMT

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