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Re: more struggles with POWDER test matierals

From: Harry Halpin <hhalpin@ibiblio.org>
Date: Wed, 13 May 2009 16:42:54 +0200
Message-ID: <b3be92a00905130742q136f0913k1613f0d71b5718cf@mail.gmail.com>
To: Phil Archer <phil@philarcher.org>
Cc: Dan Connolly <connolly@w3.org>, public-powderwg <public-powderwg@w3.org>, www-tag@w3.org
On Wed, May 13, 2009 at 4:07 PM, Phil Archer <phil@philarcher.org> wrote:
> Hi Dan,
>
> Thanks as always, for taking the time to look at our work. We've been
> through your comments, done some tests, made some discoveries and made some
> minor tweaks to a couple of things.
>
> Comments inline.
>
>
> Dan Connolly wrote:
>>
>> In our 23 apr meeting*, the TAG reviewed my comment about
>> the testcases not working:
>>  powder-test/grddl/powder002.xml is 404?
>>  http://lists.w3.org/Archives/Public/public-powderwg/2008Dec/0006.html
>>
>> and decided to endorse it. It's hard for us to review POWDER
>> with the test materials in their present state.
>>
>> Is there some way of using the test materials in their present
>> state that we're just not aware of? Or are they actually broken
>> and in need of a fix?
>
> Taking your original e-mail, the test suite URI works:
> http://www.w3.org/TR/powder-test/#grddl and if you follow the links from
> there to, say,
> http://www.w3.org/TR/powder-test/tests/grddl_tests/Manifestgrddl002.rdf the
> files referenced within that are all present and correct. i.e. there are no
> 404s in the chain. I verified this with a script, accessible at the very end
> of our implementation report [1]. In other words, past errors in this regard
> have already been corrected.
>
> The more substantive point you've raised concerns our GRDDL references.
>
> We did some tests with two applications: the W3C GRDDL service (which is
> based on Redland) and Jena which uses the Saxon XSLT engine. Both
> applications gave error messages but for different reasons.
>
> We can't be 100% sure but it seems very likely that the reason that Redland
> fails is because we use XSLT2.
>
> We are more sure that the reason that Jena fails is that it doesn't parse
> XML namespace documents to find the data-view transformation link - which is
> the GRDDL method we use.
>
> Redland gives a parsing error, Jena (Saxon) tries to validate against the
> RDFa DTD and throws out many lines of errors.
>
> It would be good to find a GRDDL implementation that supported both XLST 2
> and schema-identified transformations. If such an application exists, we'd
> be interested to see the result (but I can't find any).
>
> We /have/ however made a slight change since your e-mail. Originally, we
> published 2 separate XSLTs. One does the POWDER to POWDER-BASE
> transformation for which XSLT 2 functions are required) and the second gets
> you from POWDER-BASE to POWDER-S (this just uses XSLT 1). Recall that the
> only difference between POWDER and POWDER-BASE is that in the latter, all
> IRI constraints are defined as regular expressions. In the former, we
> support more friendly constraints like 'inclduehsosts.'
>
> Originally we had data-view:transform links to both of those stylesheets
> separately in the POWDER schema which actually comprises multiple files.
> That was a mistake that we've now corrected. The GRDDL reference now is to a
> single XSLT that is an exact copy of the P to P-B stylesheet with an
> additional <xsl:include /> element pointing to the P-B to P-S transform
> (unchanged).
>
> We've tested this combined file in Saxon (directly and via W3C XSLT service)
> and it works fine. For example, if you put GRDDL test 2 and the combined
> XSLT into the W3C service, you get the (correct) result as can be seen at
> http://tinyurl.com/q9ljkh.
>
> The separate XSLTs are still available and will remain so, along with a
> script I wrote that does the P to P-B transformation, so that it is possible
> to do the full transformation through to POWDER-S without using XSLT 2.
>
> It's clear that we're pushing the limits of what GRDDL can do, however,
> technologies other than XSLT 1 are expressly allowed in the GRDDL spec, as
> are schema-defined transformations.
>
> I hope this answers your concerns.

Yes, I concur with Phil. This is precisely a problem due to the
combination of XSLT2, schema include support, and GRDDL it appears,
*not* a broken test-case for POWDER per se. Note that due to XSLT2 not
being requested (and I did ask I believe if there was interest), we
did not have this test-case in the GRDDL Test Cases. However, my
question for Phil: Is it possible to do this without schema includes
or XSLT2? I assume the answer is no, but if this is mission-critical
code, then it would be better to have everything done in a single
schema without schema includes and using XSLT 1. Of course, I am
assuming POWDER has excellent reasons for using XSLT2+schema includes.


> Phil.
>
>
>
>
>
> [1] http://www.w3.org/2007/powder/Group/features.html
>>
>>
>> * minutes pending; draft in member space:
>> http://lists.w3.org/Archives/Member/tag/2009Apr/att-0051/23-minutes.html
>>
>> p.s. tracker, this is re ACTION-262
>>
>
> --
>
> Phil Archer
> http://philarcher.org/www@20/
>
> i-sieve technologies                |      W3C Mobile Web Initiative
> Making Sense of the Buzz            |      www.w3.org/Mobile
>
>
Received on Wednesday, 13 May 2009 14:43:30 GMT

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