W3C home > Mailing lists > Public > public-xml-processing-model-wg@w3.org > October 2006

Re: GRDDL WG liaison

From: Alex Milowski <alex@milowski.org>
Date: Fri, 13 Oct 2006 10:55:43 -0700
Message-ID: <452FD31F.20805@milowski.org>
To: XProc WG <public-xml-processing-model-wg@w3.org>

Murray Maloney wrote:
> A question has arisen about whether a 'GRDDL-aware agent' can/should process
> an XIncludes in the source before/after executing the transformation 
> resource.
> At first look, I thought that such a decision was best left to a policy 
> of the agent.
> That is, I thought that each agent would be able to decide how it would 
> process
> the source file and what it would do with the result. After all, the 
> markup is only
> intended to tell you that the grddl:transformation relationship exists, 
> not what an agent
> is supposed to do with that knowledge.
> 
> 
> Anyway, it is not clear to me whether this WG has an obligation to 
> address the
> question of when XInclude processing should be performed, or whether that
> is simply a question left to local policy decisions. It occurred to me 
> along the way
> that  'GRDDL-aware agents' could effectively use XML Pipelines to 
> describe their
> processing policies.

Well, to some extent, we had addressed this issue in that we have
a pipeline language that lets a user describe when xinclude processing
should happen.

The problem here is whether an XML pipeline is too much detail
about the actual processing.

I could imagine addressing this issue using XProc as a conceptual
backing so that some combination of annotations directly
translate into a construction of a specific XML pipeline.

> 
> Just to complicate the issue, someone pointed out that the source 
> document might
> in fact be a language variant that had been served from a given URI in 
> response
> to user preference for Spanish, for example. In that case, if you pass 
> the URI of
> the source to an XSLT transform, it will more likely retrieve the 
> default variant
> of English, for example. The result would be an RDF restatement of the 
> English,
> not the intended Spanish variant. I wondered whether any XML Pipelines 
> components
> would have offer a way to perform content negotiation.

In the past, I have used a custom "URL" component to interact with
HTTP resources--setting specific header values necessary to
interact with a URI identified resource.  While we have the
mechanism for this kind of component to exist (e.g. a
custom component) and be controlled, I'm not sure we've signed up as a
WG to spec such a component.

I would certainly like to explore that option as I've found my "url
action" step very useful.

> Also there was a question related to base URI which I did not fully fathom.

I suspect they have a similar issue to us in that after a number of
these transformation steps what is the base URI of a document
or element?  If they are wrestling with that issue, we should make
sure that we have similar answers.

It wouldn't be good for one specification (GRDDL) that has a step-wise
processing model to have a different answer than XProc in terms of
base URI values.



-- 
--Alex Milowski

"The excellence of grammar as a guide is proportional to the paucity
of the inflexions, i.e. to the degree of analysis effected by the
language considered."

Bertrand Russell in a footnote of Principles of Mathematics
Received on Friday, 13 October 2006 17:55:54 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 8 January 2008 14:21:49 GMT