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Re: Comment on RDFa 1.1 Core: Profiles, term mappings, and URIs as literals

From: Ivan Herman <ivan@w3.org>
Date: Fri, 6 Aug 2010 07:40:04 +0200
Cc: public-rdfa-wg@w3.org
Message-Id: <633C972B-49E0-460D-AD8E-2F74EFC87AA8@w3.org>
To: Richard Cyganiak <richard.cyganiak@deri.org>
Hi Richard,

(I am still on vacations, so I may not answer to your possible answer quickly, but I will become more active next week...)

This was discussed several times on the mailing list and I fully understand your issues. Here is the reason I was in favour of the current setup, but I am absolutely open to discussion because, well, it does complicate processing (speaking as an implementer).

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
- 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 


resource which are definitely not intended and are meaningless for foaf...

These were my modeling fears that led me to the current proposal, in spite of being more awkward.

Try to convince me that I am wrong! Please:-)



(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:-)
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/
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Received on Friday, 6 August 2010 05:39:04 UTC

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