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URI aliases for RDF terms?

From: Ivan Herman <ivan@w3.org>
Date: Wed, 2 Nov 2011 10:43:22 +0100
Message-Id: <B3EC7275-112E-492B-BE65-E1CD98A07491@w3.org>
To: W3C RDF WG <public-rdf-wg@w3.org>
I thought that this working group needs some more discussions, because we have already solved all our issues:-)

More seriously: there is an issue on which this WG, maybe, could/should have an opinion. There is a long discussion going on in the Data in HTML SWIG Task Force[1], while looking at the microdata->RDF mapping. The issue is around the ugly URI that one has to use for rdf:type...


- at present, an item in microdata can only have one type, that is syntactically accepted via their @itemtype attribute
- people have expressed the need to have several types for a single entity
- the only way to do it now is to explicitly 'encode' a type in microdata, something like

<link itemprop="http://www.w3.org/1999/02/22-rdf-syntax-ns#type" href="http://type.example.org" />

- there is no way in microdata to abbreviate a URI with a prefix:extension syntax, ie, to be able to write rdf:type. In other terms, users _must_ write down the full URI. Let us face it, nobody can remember that stuff (I know I can't:-)
- the solution that is emerging is to define a separate 'type' attribute in, say, schema.org, ie, that people could say

<link itemprop="http://schema.org/type" href="URI-to-Type" />

because people might remember that more easily (which is true). Then... I presume microdata->RDF mappings would have to _know_ that particular attribute and turn it into rdf:type. This is really ugly, but that is the direction things seem to go.
(- of course, the proper solution would be for microdata to allow several types in one statement (like RDFa allows). But the microdata community is reluctant to do that.)

This discussion does raise a more general issue, however: does it make sense for us to think in terms of URI aliases for the RDF(S) terms? Something like http://www.w3.org/rdf/type, or something similar. It would make the human authoring of RDF easier (even if all RDF syntaxes allow for some sort of a prefix definition, which greatly alleviates the problem).

I realize this may be a huge can of worms, in terms of deployed applications, specifications, etc. In other words, probably the only way to do that would be to define some sort of a canonical alias? redirection? etc, of humanly readable URI-s to the current ones. And even that may be hairy. But it may be worth some discussions...



[1] http://www.w3.org/wiki/Html-data-tf

Ivan Herman, W3C Semantic Web Activity Lead
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Received on Wednesday, 2 November 2011 09:41:18 UTC

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