W3C home > Mailing lists > Public > www-archive@w3.org > August 2008

Re: GRDDL

From: Julian Reschke <julian.reschke@gmx.de>
Date: Wed, 06 Aug 2008 18:23:52 +0200
Message-ID: <4899D018.4000006@gmx.de>
To: Henri Sivonen <hsivonen@iki.fi>
CC: Toby A Inkster <tai@g5n.co.uk>, Justin James <j_james@mindspring.com>, www-archive <www-archive@w3.org>

Henri Sivonen wrote:
> Going off-topic for public-html. -public-html +www-archive

I don't think it is off-topic, but anyway...

>> No, it doesn't even scale for them. For instance, in the HTML I 
>> produce I could specific conventions (classnames, link relations, 
>> whatever) to embed metadata. A generic transformer for HTML wouldn't 
>> be able to handle that.
> 
> If you use conventions specific to your site, you are venturing outside 
> the well-known part. If you serve a program that transforms your 
> specific syntax to RDF, you move the point where a well-known vocabulary 
> is needed to the RDF layer, but concrete common ground with the 
> information consumer has to come somewhere. However, making the consumer 

I'm not sure what you're talking about. The GRDDL transform might 
extract information from custom markup patterns, but produce statements 
using publicly known URIs.

> run a foreign XSLT program has the scalability problem of crawlers being 
> able to execute programs in large quantities. With Validator.nu, the 
> main scalability program seems to be the ability to execute Schematron, 
> which is implemented by compiling the Schematron schema into XSLT and 
> running the XSLT program.

We discussed this already over on public-html. There are many ways to 
publish RDF, some are:

- publish RDF in XML or N3...
- publish HTML with embedded RDFa
- publish HTML with microformats
- publish HTML with GRDDL
- do the latter, but run the transform on the server, essentially 
publishing both HTML and RDF

...and so on.

No recipient is *forced* to run the GRDDL transformation.

> Moreover, for class-based syntaxes, a transformer that contains its 
> executable parts (whether in XSLT or in another programming language) 
> only needs to cover the kind of syntax that a given application is 
> interested in consuming. If I'm looking for hCard data and my 
> application understands RDF vCard, I only need a transformation from 
> hCard to RDF vCard. I don't need a solution that scales to all 
> microformats.

Yes. So? As far as I can tell, nobody claimed that GRDDL necessarily is 
the right solution to *every single* use case one can think of. If you 
only look for address book data, you can still consume generic RDF and 
just extract the properties you're interested in.

>>> If you are serving a document in your vocabulary and a program that 
>>> makes sense of it, are you really communicating with others by 
>>> sending semantic markup or are you communicating by sending programs? 
>>> If you made your markup empty and embedded all the data in the 
>>> transformation program, would the recipient know any difference?
>>
>> I don't see how that is relevant. What's relevant is what the 
>> recipient gets. And of course the intent of GRDDL is to have a single 
>> transform for a vocabulary, and to reuse that transform for each 
>> instance document. You could use it in a different way, but who cares?
> 
> http://lists.w3.org/Archives/Public/www-tag/2008Jul/0164.html

That doesn't seem to be reply to the thing we were discussing, it's just 
re-stating that forcing clients to run code to read information is bad. 
Agreed.

The situation the quote on the TAG list is about is Flash, which is not 
crawlable *at all* without running custom code (at least that's the 
concern). This is not the case for HTML+GRDDL; the HTML code is 
available as it should be.

If what you want is a way to embed generic RDF without having to serve 
multiple documents, or by letting the client run code, RDFa seems to be 
one potential solution.

BR, Julian
Received on Wednesday, 6 August 2008 16:24:40 UTC

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