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Re: Interesting experience: my foaf in RDFa

From: Dan Brickley <danbri@danbri.org>
Date: Fri, 24 Aug 2007 22:55:32 +0100
Message-ID: <46CF53D4.7040103@danbri.org>
To: "Hausenblas, Michael" <michael.hausenblas@joanneum.at>
CC: Ivan Herman <ivan@w3.org>, W3C RDFa task force <public-rdf-in-xhtml-tf@w3.org>, eyal.oren@deri.org, Frédérick Giasson <fred@fgiasson.com>

Hausenblas, Michael wrote:
> 
> Ivan,
> 
>> - It works!  This is a really important point: I did not find 
>> any construction in my previous foaf file that I could not 
>> express somehow.
> 
> Good to hear that! I made some experiments some time ago (switching
> from RDF/XML to RDFa [1]) and can by and larger conform your observations.

Yep, good to know! :)

There are some relatively intricate things expressible in FOAF, around 
chat IDs, groups, schoolhomepages, online accounts etc --- I'd be 
interested to see some of these expressed in a pretty howto page.

> However, one thing _really_ bugs me: Our nice (X)HTML+RDFa documents are
> ignored by 'Semantic Web search engines' as ptsw [2] or sindice [3]. 
> People, move on!

Can I put in a vote for W3C to spend some effort on updating the RDF 
Validator (http://www.w3.org/RDF/Validator)? I reckon that, alongside 
the syntax checker at validator.w3.org, will go a long way to pushing 
these developments out into wider usage.

The next thing I try in RDFa will probably be expressing (a subset?) of 
the FOAF schema in the FOAF spec. Not really sure what that should look 
like, but ... would be nice for that doc to have a "valid html" icon in it!

>> Do not crucify me: maybe we should have (as some sort of a 
>> very edge case advanced feature) some sort of an import 
>> mechanism. Something like
>>
>> <link rel="rdfa-import" href="...."/>
> 
> As I see the benefit and the use I do support your proposal, though
> the concrete solution you propose seems a bit awkward to me. 
> Mark? Any thoughts?

Isn't this re-inventing iframes? How should an RDFa parser pointed at 
dan.html deal with an iframe that includes photos.html ?

cheers,

Dan

> Cheers,
> 	Michael
> 
> [1] http://sw-app.org/mic.xhtml
> [2] http://pingthesemanticweb.com
> [3] http://sindice.com
> 
> ----------------------------------------------------------
>  Michael Hausenblas, MSc.
>  Institute of Information Systems & Information Management
>  JOANNEUM RESEARCH Forschungsgesellschaft mbH
>  Steyrergasse 17, A-8010 Graz, AUSTRIA
> ---------------------------------------------------------- 
> 
>> -----Original Message-----
>> From: public-rdf-in-xhtml-tf-request@w3.org 
>> [mailto:public-rdf-in-xhtml-tf-request@w3.org] On Behalf Of 
>> Ivan Herman
>> Sent: Friday, August 24, 2007 12:39 PM
>> To: W3C RDFa task force
>> Subject: Interesting experience: my foaf in RDFa
>>
>> I decided to experiment with RDFa with a slightly more 
>> complex example.
>> I used to have my foaf file[1] only in RDF/XML, ie, edit it, 
>> update it, etc, in that format. I now created an XHTML/RDFa 
>> version of it[2] and from now on my intention to update [2] 
>> and generate [1] automatically (as an extra bonus my 
>> non-informational URI[3] redirects to either the html or the 
>> rdf file, depending on the HTTP request).
>>
>> My foaf file is fairly complex, and it mixes a good number of 
>> namespaces (I always used it as some sort of an experiment to 
>> express different things). Putting it into RDFa was a bit of 
>> a challenge here and there, but it was worth it. Some experiences:
>>
>> - It works!  This is a really important point: I did not find 
>> any construction in my previous foaf file that I could not 
>> express somehow.
>> And that is really important; it is a one-time evidence that 
>> we do have something good here.
>>
>> - It is an authoring challenge (this is not unlike 
>> microformats). Of course, editing the file in a screen editor 
>> is possible but makes it a bit difficult to follow and is 
>> error prone. The problem with a WSWYG editor like Amaya is 
>> that editing the attributes is sometimes a bit complicated. 
>> What you need is an editor that makes it easy to switch 
>> between WYSWYG and source view but most of them mean moving 
>> to another window and thereby loosing context. My best 
>> experience is with Adobe GoLive which allows (in the WYSWG 
>> window) to have a pop up window on a specific element with 
>> all the xml source editable. That helps a lot...
>>
>> - It can be a bit convoluted sometimes. No real surprise 
>> there: if you look at [2] you can see that I tried to 
>> incorporate some sioc statements and turning that into RDFa 
>> was a bit complicated. Well, the sioc statements themselves 
>> are convoluted....
>>
>> This means that some of the RDF constructs become a bit 
>> unnatural in HTML, if you want to add some humanly readable 
>> text to it. Which raises a practical question. What if the 
>> author wants to keep some of what he/she wants to express in 
>> RDF/XML and would like to 'bind' it to the RDF extracted from 
>> HTML? My solution was to add a <link> statement with 
>> rel="rdfs:seeAlso", but this relies on the RDF environment to 
>> understand and interpret that.
>>
>> Do not crucify me: maybe we should have (as some sort of a 
>> very edge case advanced feature) some sort of an import 
>> mechanism. Something like
>>
>> <link rel="rdfa-import" href="...."/>
>>
>> which means that the end result should be the merge of the 
>> value of @href and the extracted RDF. I am not sure... just 
>> raising the possibility here...
>>
>>
>> Ivan
>>
>>
>>
>> [1] http://www.ivan-herman.net/foaf.rdf
>> [2] http://www.ivan-herman.net/foaf.html
>> [3] http://www.ivan-herman.net/Ivan_Herman
>> -- 
>>
>> Ivan Herman, W3C Semantic Web Activity Lead
>> Home: http://www.w3.org/People/Ivan/
>> PGP Key: http://www.ivan-herman.net/pgpkey.html
>> FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Friday, 24 August 2007 21:55:40 GMT

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