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RE: Issue rdfms-abouteach

From: Dan Brickley <danbri@w3.org>
Date: Fri, 16 Nov 2001 06:15:43 -0500 (EST)
To: <Patrick.Stickler@nokia.com>
cc: <jjc@hplb.hpl.hp.com>, <dave.beckett@bristol.ac.uk>, <w3c-rdfcore-wg@w3.org>
Message-ID: <Pine.LNX.4.30.0111160605030.15883-100000@tux.w3.org>
On Fri, 16 Nov 2001 Patrick.Stickler@nokia.com wrote:

>
> It is a useful syntactic convenience for folks who
> write their RDF/XML instances by hand. One can
> put a bunch of resources in a bag and then make
> an aboutEach statement. It also IMO can help make
> an RDF instance more readable with regards to
> common classifications of resources. E.g.
>
> <rdf:Bag rdf:ID="guys">
>    <rdf:li rdf:resource="#Bob"/>
>    <rdf:li rdf:resource="#John"/>
>    <rdf:li rdf:resource="#Joe"/>
>    <rdf:li rdf:resource="#Harry"/>
>    <rdf:li rdf:resource="#Frank"/>
>    <rdf:li rdf:resource="#Phil"/>
> </rdf:Bag>
>
> <rdf:Bag rdf:ID="gals">
>    <rdf:li rdf:resource="#Mary"/>
>    <rdf:li rdf:resource="#Elain"/>
>    <rdf:li rdf:resource="#Jane"/>
>    <rdf:li rdf:resource="#Betty"/>
>    <rdf:li rdf:resource="#Elizabeth"/>
>    <rdf:li rdf:resource="#Judeth"/>
> </rdf:Bag>
>
> <rdf:Description rdf:aboutEach="#guys">
>    <rdf:type rdf:resource="x:Male"/>

We can't put a qname 'x:' there, so this would have to be

    <rdf:type rdf:resource="http://example.org/schema#Male"/>

...slightly less prettier than doing it inline with a typedNode:

    <rdf:li><x:Male rdf:about="#phil"/></rdf:li>

...that said, your general point is fair: some things (eg. ascribing
further properties about each item) would be prettier/easier. Until you
feed the RDF/XML to a parser that doesn't implement this bit of the M&S
spec.

In my experience, 'aboutEach' is in the category of 'nice try, but we
didn't quite get it right'. I support a decision to drop it,
*so long as* we give fair warning on www-rdf-interest and elsewhere that
this is our plan, and so long as we listen carefully to objections and
concerns from the implementor community.

One way of doing this would be to offer an account of how DAML+OIL, and
hence potentially the new WebOnt WG's ontology language, offer similar
facilities couched in terms of the graph data model.



> </rdf:Description>
>
> <rdf:Description rdf:aboutEach="#gals">
>    <rdf:type rdf:resource="x:Female"/>
> </rdf:Description>
>
> This is also very useful for asserting "local"
> classifications of resources for third-party
> knowledge where you cannot touch the original
> schemas.

I've not seen any deployment evidence of it being used in a
distributed/hyertext style, though I agree this would've been consistent
with the original goal. There are other ways of achieving the same end,
either writing out the markup longhand or using an ontology language such
as DAML+OIL.


> I know of one standards group which is in the
> process of finalizing the decision to migrate
> to RDF and is planning on using aboutEach a good
> deal, though I'm not at liberty (yet) to say who
> that is.

Perhaps you could alert them to the possibility that we are considering
dropping this feature of the language? Or, if/when we make such an
'advance warning' statement on www-rdf-interest, make sure it gets passed
on to them.

cheers,

Dan

>
> *Please* leave it alone.
>
> Cheers,
>
> Patrick
>
Received on Friday, 16 November 2001 06:16:57 EST

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