Validating SVG+RDF

[Doug Schepers-3]

Hi, Guys-

I put an RDF license in an <svg:metadata> element, as is common practice
for Inkscape-generated content, and tried to validate it.  The validator
complained, no matter which method I tried, either including the
necessary namespaces in the RDF root [1], or in the SVG root [2].
Either should be legal, and should validate (unless I'm confused).

This is problematic for 2 reasons:

1) the SVG spec explicitly uses examples of this
2) there is a lot of SVG content (mostly generated by Inkscape) on
Wikipedia, which wants the license info to be clear.

There are other combo options that the validator claims to understand,
including XHTML + RDFa, XHTML 1.1 plus MathML 2.0, XHTML 1.1 plus MathML
2.0 plus SVG 1.1.  Is it possible to get RDF put into that list?

More concretely, are there specific problems that make that difficult?
Is there something I can do to help with the issue?

(Note that Validator.nu doesn't validate RDF at all, so no help there.)

[1] http://www.schepers.cc/svg/rdf/license1.svg
[2] http://www.schepers.cc/svg/rdf/license2.svg
[3] http://upload.wikimedia.org/wikipedia/commons/0/0e/Inkscape_logo_2.svg

Regards-
-Doug Schepers
W3C Team Contact, SVG and WebApps WGs

[olivier Thereaux]

Hi Doug.

On 8-Mar-09, at 10:45 PM, Doug Schepers wrote:
> I put an RDF license in an <svg:metadata> element, as is common  
> practice for Inkscape-generated content, and tried to validate it.

Once you start mixing XML dialects, a DTD based validator can't help  
you. True, we do have some DTDs for compound documents such as XHTML  
1.1 plus MathML 2.0 plus SVG 1.1 but they only allow unflexible usage  
of XML mix-and-match (in particular, no flexibility at all regarding  
namespaces).

> There are other combo options that the validator claims to  
> understand, including XHTML + RDFa, XHTML 1.1 plus MathML 2.0, XHTML  
> 1.1 plus MathML 2.0 plus SVG 1.1.  Is it possible to get RDF put  
> into that list?

If the SVG WG wants to produce an SVG+RDF DTD, it would be easy to  
validate with any old-school DTD validator, with the limitations  
mentioned above. I suspect the SVG WG won't want to do that – it has  
been its policy to shun DTDs for a while, and rightly so.

The tool you really want for validation of SVG+RDF is an nVDL  
dispatcher, combined with DTD+XMLSchema+RelaxNG(+Schematron)  
validation capabilities.

IIRC Henri's validator.nu has such capabilities - although I don't  
know how difficult it would be to check RDF with that engine -. So  
does relaxed, a project that was really promising, but which I'm not  
sure is still actively attended. The online service is done most of  
the time, the sourceforge page (http://relaxed.sourceforge.net/) shows  
little activity, and I haven't managed to get hold of Petr (the  
developer) in a while, although for some time we were looking at  
hosting relaxed at W3C…

How hard would it be to have this on validator.w3.org? Not trivial,  
but feasible. I invite you to review (with the WG) the validator's  
development roadmap, which looks into this question:
http://qa-dev.w3.org/wmvs/HEAD/todo.html#roadmap

--
olivier

[rubys]

olivier Thereaux wrote:

>
> The tool you really want for validation of SVG+RDF is an nVDL
> dispatcher, combined with DTD+XMLSchema+RelaxNG(+Schematron) validation
> capabilities.
>
> IIRC Henri's validator.nu has such capabilities - although I don't know
> how difficult it would be to check RDF with that engine -. So does
> relaxed, a project that was really promising, but which I'm not sure is
> still actively attended. The online service is done most of the time,
> the sourceforge page (http://relaxed.sourceforge.net/) shows little
> activity, and I haven't managed to get hold of Petr (the developer) in a
> while, although for some time we were looking at hosting relaxed at W3C…

I'll note that there are a few files with names including the string
'rdfa' in the "syntax" directory for validator.nu:

     http://svn.versiondude.net/whattf/syntax/trunk/relaxng/

- Sam Ruby

[Henri Sivonen]

Hi,

On Mar 9, 2009, at 14:49, olivier Thereaux wrote:
> The tool you really want for validation of SVG+RDF is an nVDL  
> dispatcher, combined with DTD+XMLSchema+RelaxNG(+Schematron)  
> validation capabilities.

Using NVDL isn't the key thing. But the relevant thing is: What level  
of checking would you like to perform on the RDF/XML data? RDFS  
validation against a particular RDF Schema? Something else?

Note that RDF/XML inside XHTML5 <head> is not an error, but there's a  
warning that no real checking in performed on the RDF/XML subtree.  
That RDF/XML doesn't work the same way in <metadata> is a bug.

> IIRC Henri's validator.nu has such capabilities - although I don't  
> know how difficult it would be to check RDF with that engine -.

In theory, one could feed Jena from the SAX events.

--
Henri Sivonen
hsivonen@...
http://hsivonen.iki.fi/

[Henri Sivonen]

On Mar 9, 2009, at 15:11, Sam Ruby wrote:

> I'll note that there are a few files with names including the string  
> 'rdfa' in the "syntax" directory for validator.nu:
>
>    http://svn.versiondude.net/whattf/syntax/trunk/relaxng/


That's part of an experiment with CURIEless RDFa syntax. It's not an  
implementation of any spec.

--
Henri Sivonen
hsivonen@...
http://hsivonen.iki.fi/

[Henri Sivonen]

On Mar 9, 2009, at 04:45, Doug Schepers wrote:

> (Note that Validator.nu doesn't validate RDF at all, so no help  
> there.)
>
> [1] http://www.schepers.cc/svg/rdf/license1.svg
> [2] http://www.schepers.cc/svg/rdf/license2.svg


Validator.nu still doesn't validate RDF, but it now skips over the RDF  
subtrees in those files more gracefully.

--
Henri Sivonen
hsivonen@...
http://hsivonen.iki.fi/

[Doug Schepers-3]

Hi, Henri-

Henri Sivonen wrote (on 4/16/09 9:09 AM):

> On Mar 9, 2009, at 04:45, Doug Schepers wrote:
>
>> (Note that Validator.nu doesn't validate RDF at all, so no help there.)
>>
>> [1] http://www.schepers.cc/svg/rdf/license1.svg
>> [2] http://www.schepers.cc/svg/rdf/license2.svg
>
>
> Validator.nu still doesn't validate RDF, but it now skips over the RDF
> subtrees in those files more gracefully.

Thanks, that's a good start!

Regards-
-Doug Schepers
W3C Team Contact, SVG and WebApps WGs