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Re: XProc: An XML Pipeline Language

From: Norman Walsh <Norman.Walsh@Sun.COM>
Date: Tue, 11 Apr 2006 07:40:27 -0400
To: public-xml-processing-model-wg@w3.org
Message-ID: <87fykk8hn8.fsf@nwalsh.com>
/ Rui Lopes <rlopes@di.fc.ul.pt> was heard to say:
| Norman Walsh wrote:
|> / Norman Walsh <Norman.Walsh@Sun.COM> was heard to say:
|> | I tinkered a bit more today, sketching a few example components in the
|> | standard library. I'm not entirely happy with the markup, the tabular
|> | summary, or the graphics. But it's a start.
| A few questions/suggestions:
| 1) "Pipelines must be acyclic. XProc does not support iteration."
| I believe the word "iteration" may be percepted as "iteration over a
| collection", instead of cycles within the pipeline graph (if I understood your
| wording correctly).

Right. I was thinking of iteration to a fixed point or for a fixed
number of iterations. There may be a component that does some
iteration, but you can't have cycles. I'll improve that wording.

| 2) "load" component: I don't undestand the difference between having this
| component instead of implicit URIs declared in some step. From your other post
| to the mailing list I understand the need for the "save" component.

It's probably not a necessary component, if we allow an href or src
attribute on a p:input element, but I still think it's probably useful
to provide it for completeness sake.

| 3) "identity" component: for clarification purposes, allowing multiple inputs
| and outputs should require explicit binding between each input/output pair?
| Something like:
| <p:step name="identity">
|   <p:input name="i1" select="somedocument" />
|   <p:input name="i2" select="anotherdocument" />
|   <p:output name="o1" select="i1" />
|   <p:output name="o2" select="i2" />
| </p:step>

No, that was just sloppy wording on my part. What I meant was that the
input pipe can accept a sequence of documents and that the output pipe
will, in that case, produce a sequence of documents. The component
only has one input and one output.

| 4) "xslt" component: being XSLT 1.0, I believe it should state "input
| document+" and "output document". Currently, the opposite is being stated.

An XSLT 1.0 processor can only have a single principle input document
(I don't know how, or if, we deal with the fact that the stylesheet
can load auxilliary documents), but it can produce multiple result
documents. (Ok, technically, it can't, but every XSLT 1.0 processor
except the MS one has an extension that does so.)

                                        Be seeing you,

Norman.Walsh@Sun.COM / XML Standards Architect / Sun Microsystems, Inc.
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Received on Tuesday, 11 April 2006 11:40:36 UTC

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