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Re: Comment on RDFa 1.1 Core: Profiles, term mappings, and URIs as literals (ISSUE-39)

From: Richard Cyganiak <richard.cyganiak@deri.org>
Date: Sat, 7 Aug 2010 23:39:52 +0200
Cc: public-rdfa-wg@w3.org
Message-Id: <6520C5D4-8D2E-4668-911B-53BEF0D31FD9@deri.org>
To: Ivan Herman <ivan@w3.org>
Hi Ivan,

On 6 Aug 2010, at 06:40, Ivan Herman wrote:
> The issue I have is that a statement like
> <http://xmlns.com/foaf/0.1/name> rdfa:term "name" .
> is a statement on a resource with a specific URI. And I see two  
> issues with that, modeling wise:
> - the goal of the @profile file is _not_ to make statements on  
> resources but to make statements on strings, ie, the way RDFa  
> processors should manipulate strings that are then converted into  
> URI-s

 From a spec writer's or implementer's point of view, you are right:  
Term mappings are about establishing mappings between different  
strings. But I think from a user's point of view, the notion that  
rdfa:term says something about a *resource* (the property or class) is  
quite intuitive. It establishes a short name for the class or  
property. So I don't think there is potential for user confusion here.

Also, I don't think that the goal of @profile is to make “statements”  
in the knowledge representation sense. The goal is to establish prefix  
mappings and term mappings. RDF triples are simply the data structure  
for writing down the mappings. For this purpose it does not matter  
between what kind of brackets or quotes you stick the string -- the  
information needed for RDFa processing is there in the data structure.

> - while you may make the statement above in your @profile file, I  
> may say in mine
> <http://xmlns.com/foaf/0.1/name> rdfa:term "blabla" .
> These are both RDF statements in RDFa files somewhere so, eg,  
> Sindice is perfectly licensed to collect both. Ie, Sindice will  
> suddenly produce a proliferation of statements on the
> <http://xmlns.com/foaf/0.1/name>
> resource which are definitely not intended and are meaningless for  
> foaf...

I don't understand why you consider this a problem. For processing any  
given HTML+RDFa document, only the @profile links contained in this  
document are used in processing. This is quite explicitly stated in  
the current draft. Other statements that may or may not exist in other  
documents are irrelevant.

I also don't see what Sindice has to do with this. Yes, Sindice can  
and will collect any and all RDF statements out there, and thus it has  
a collection full of incorrect and contradictory claims. However it  
never merges them into a single RDF graph. It always remembers the URL  
of the document (graph name) where it found any statement. Thus,  
nothing of the intention or meaning is lost.

> (As an aside, if we had literals as subjects that we could use those  
> instead of the URI Resource, but that opens a whole lot of other  
> issues:-)

(Even if we had literals as subjects, I'd still say that a URI should  
be used here!)


> On Aug 5, 2010, at 12:53 , Richard Cyganiak wrote:
>> Hello RDFa WG members,
>> This is a comment on Profiles in the latest RDFa WD [1]. The draft  
>> provides a mechanism for establishing term mappings using RDF  
>> triples of the following general shape:
>>   ?x rdfa:term "name" .
>>   ?x rdfa:uri "http://xmlns.com/foaf/0.1/name" .
>> I ask that the mechanism be changed to the following form:
>>   <http://xmlns.com/foaf/0.1/name> rdfa:term "name" .
>> This change should be made for the following reasons:
>> 1. Conciseness. If one triple is enough to say it, there should be  
>> one triple.
>> 2. Putting URIs into RDF literals is almost always an anti-pattern.
>> 3. The principle of least surprise.
>> 4. Using a URI simplifies the creation of self-contained profiles  
>> that contain a set of term mappings along with labels for the  
>> classes and properties, mappings to other vocabularies,  
>> presentation hints etc.
>> 5. Using a URI simplifies the extension of existing RDF Schema  
>> documents (e.g., the RDF version of the FOAF spec) to RDFa profiles.
>> Best,
>> Richard
>> [1] http://www.w3.org/TR/2010/WD-rdfa-core-20100803/
> ----
> Ivan Herman, W3C Semantic Web Activity Lead
> Home: http://www.w3.org/People/Ivan/
> mobile: +31-641044153
> PGP Key: http://www.ivan-herman.net/pgpkey.html
> FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Saturday, 7 August 2010 21:40:29 UTC

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