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Re: PSVI issues

From: Henry S. Thompson <ht@inf.ed.ac.uk>
Date: Thu, 08 May 2008 15:00:14 +0100
To: Norman Walsh <ndw@nwalsh.com>
Cc: public-xml-processing-model-wg@w3.org
Message-ID: <f5b63tozyj5.fsf@hildegard.inf.ed.ac.uk>

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Norman Walsh writes:

> By which you mean, you'll write
>
>  <p:pipeline psvi-required="true">
>    ...
>
> And any impl. that don't support PSVI annotations will simply refuse
> to execute it. Yes?

Yes.

> | 3) Having said that, I think it _does_ make sense to provide a means
> |    for pipeline authors to do something at runtime depending on PSVI
> |    support.  But I think the minimum necessary to declare victory is
> |    just psvi-available(), which if true means the processor claims
> |    it's passing PSVI information along.  No granularity or locality is
> |    implied, that is, the value should be the same at all times/places
> |    within a given episode.
>
> That's what I thought I wanted last week and I was convinced on the
> call that all I really wanted was psvi-supported(). Do you think
> that's no longer sufficient?

See example sent per Mohamed's request. . .

> |    b) Implementations SHOULD preserve PSVI properties across steps
> |       insofar as that is consistent with step semantics.  It is
> |       implementation-defined what PSVI properties it supports overall,
> |       and what PSVI properties are lost by what steps.
>
> I have mixed feelings. Consider p:delete. Does it make sense for that
> step to preserve PSVI properties on elements and attributes that it
> doesn't delete?

Good point.  We could consider saying "Implementations MUST ensure the
accuracy of the PSVI properties they preserve.  Since almost any
structural modifications may render any validation-related properties
inaccurate, implementations MAY discard all PSVI properties in the
output of structure-modifying steps (as an alternative to preserving
only those known to be unaffected)."

And "So, for example, it is implementation-defined whether a
PSVI-supporting processor preserves PSVI properties on the documents
passed to the subpipeline of p:viewport"

> Or maybe we could say that PSVI properites can only appear on the
> output of the validate steps, p:xslt, and p:xquery (and user-defined
> steps).

I'd hate to go there, but maybe we have no choice.

ht
- -- 
 Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                     Half-time member of W3C Team
    2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
            Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
                   URL: http://www.ltg.ed.ac.uk/~ht/
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Received on Thursday, 8 May 2008 14:01:02 GMT

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