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Best practices - how to avoid duplication

From: Charles McCathieNevile <charles@w3.org>
Date: Thu, 4 Dec 2003 10:58:07 -0500 (EST)
To: elacazed <elacazed@actia.fr>
Cc: www-rdf-interest@w3.org
Message-ID: <Pine.LNX.4.55.0312041047170.20086@homer.w3.org>

Hi,

(This isn't necessarily a description of THE best practice. Just stuff that I
think would help).

The question is whether there is some way to know that the two literals are
the same thing (both as a matter of the spec, and in the tools that are
interpreting it). To get around the issue you could use something like

<author>
   <entity rdf:resource="#author1"/>
</author>
<approved>
   <entity rdf:resource="#author1"/>
</approved>
...
<rdf:Description rdf:about="author1">
  <entity>
    name, code, ...


there is an example of how this works in
http://www.w3.org/2001/sw/Europe/200305/axforms/earlins.rdf where there are
about 70 items that all have the same earl:Assertor and the same earl:subject
so those two things are described once at the beginning.

Finally, I would suggest that you use something other than a direct URI to
identify a person, since it then becomes impossible to know whether you are
really referring to the person, or to what ever is at the URI. Foaf -
http://xmlns.com/foaf/0.1/ - does this by using

<foaf:Person>
  <foaf:mbox rdf:resource="mailto:me@my.address"/>

which seems to work very nicely. (Actually they use another property as well,
to hide the real address from spammers).

But this is an ongoing argument in this group - there are people who don't
agree with that last point.

(By the way you should probably include a subject in your email, so that it
doesn't look like spam)

cheers

Chaals

On Thu, 4 Dec 2003, elacazed wrote:

>
>Hi,
>
>It's me again.
>
>I've succeeded in adding RDF data to my XML files, and I have an XML Schema to
>validate the xml files... But I still have some problems :
>
>In our data, we can have several instances of the same resource (IE : an entity,
>such as a society, might appear several times)
>
>For example :
>
><rdf:RDF>
>    <rdf:Description rdf:about="http://...">
>    <!-- author -->
>    <author>
>        <rdf:Description rdf:about="mailto:elacazed@actia.fr">
>            <firstName>Etienne</firstName>
>            <name>Lacazedieu</name>
>            <entity>
>                <rdf:Description rdf:about="http://www.actia.fr">
>                    <code>ACTIA</code>
>                    <name>actia</name>
>                </rdf:Description>
>            </entity>
>        </rdf:Descritpion>
>    </author>
>    <approval>
>        <rdf:Description rdf:about="mailto:validator@actia.fr">
>            <firstName>John</firstName>
>            <name>Validator</name>
>            <entity>
>                <rdf:Description rdf:about="http://www.actia.fr">
>                    <code>ACTIA</code>
>                    <name>actia</name>
>                </rdf:Description>
>            </entity>
>        </rdf:Descritpion>
>    </approval>
>....
>
>My problem is that when the RDF graph is built, the resource
>"http://www.actia.fr" appears correctly, as the objet of 2 predicates (entity),
>but the name and code of the resource appear twice!
>
>Is there a way to fix this???
>
>Another problem is that if the exemple above is correct for an RDF parser, I
>could not find a way to validate this with an XML schema, unless all the
>elements are in the rdf: namespace....I'm aware that it's more an XML Schema
>related question, but if you know a solution to "mix" namespaces like this, It
>would be really great!
>
>Thanks for your answers,
>
>Etienne Lacazedieu
>

Charles McCathieNevile  http://www.w3.org/People/Charles  tel: +61 409 134 136
SWAD-E http://www.w3.org/2001/sw/Europe         fax(france): +33 4 92 38 78 22
 Post:   21 Mitchell street, FOOTSCRAY Vic 3011, Australia    or
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Received on Thursday, 4 December 2003 11:03:03 GMT

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