Re: result documents in an XSLT step?

Dear Gerrit (cc xproc-dev),

Thank you for the quick and helpful response. I was, indeed, using a
file-system URI (sigh!), and prepending "file:///" resolved the error.
Adding the <p:for-each> over the secondary output port then stored the
result documents as expected.

Best,

David

On Sat, Oct 31, 2020 at 3:19 PM Imsieke, Gerrit, le-tex <
gerrit.imsieke@le-tex.de> wrote:

> Hi David,
>
> Have you tried writing the result to
> file:///Users/djb/repos/cz/output/verb-1a.xml?
>
> XProc 3 has become a bit stricter about conformant URIs.
>
> Also when you said you provided an absolute path as the base URI, did
> you provide an /os/path or did you provide an actual file:///os/path URI?
>
> You might use the function p:urify() on OS paths in order to get URIs,
> but I’m not sure about the implementation status in Morgana.
>
> And when you specified <p:output port="secondary" sequence="true"/>, did
> you connect the output to the secondary output of your XSLT step?
>
> If you want to store the secondary outputs of the XSLT step named
> 'generate' to disk, you need to do something like
>
> <p:for each>
>    <p:with-input pipe="secondary@generate"/>
>    <p:store href="{base-uri()}"/>
> </p:for-each>
>
> Grouping in XProc isn't that powerful. There’s a group-adjacent option
> in p:wrap-sequence, but grouping XML by a common value is best done in
> XSLT.
>
> Gerrit
>
>
> On 31.10.2020 20:02, David Birnbaum wrote:
> > Dear xproc-dev,
> >
> > I would be grateful for advice about how best to manage a pipeline that
> > requires me to generate and then continue to process multiple output
> > documents from a single input. The input contains 110k <item> elements
> > that are distinguished by a @paradigm attribute on the <item> element;
> > there are about 150 different @paradigm values in the input. I would
> > like to group the <item> elements by their @paradigm values, process
> > each group, and write the outputs for each group separately to disk. I
> > would also like to run another transformation over those outputs and
> > write the results of that transformation to disk, as well. I have poked
> > at the following approaches and run into trouble with both of them,
> > probably because (or, at least, partially because) I am not (yet, I
> > hope!) very adept at XProc:
> >
> > 1. Within the XProc, I run an XSLT step that uses <xsl:for-each-group>
> > and <xsl:result-document> to create separate output for each group, with
> > constructed output @href values. This errors out with:
> >
> > <c:errors xmlns:c="http://www.w3.org/ns/xproc-step
> > <http://www.w3.org/ns/xproc-step>"><c:error code="err:XC0121"
> > name="generate" type="p:xslt"
> > href="file:///Users/djb/repos/cz/pos/verb/verb.xpl" line="64"
> > column="27" xmlns:p="http://www.w3.org/ns/xproc
> > <http://www.w3.org/ns/xproc>"
> > xmlns:err="http://www.w3.org/ns/xproc-error
> > <http://www.w3.org/ns/xproc-error>"><message>URI
> > '/Users/djb/repos/cz/output/verb-1a.xml' of secondary result is not
> > valid or not absolute.</message></c:error></c:errors>
> >
> > I had first tried a relative path for the @href on the
> > <xsl:result-document>, and I thought the error message meant that there
> > was no base URI within the pipeline, so I specified an absolute path
> > instead, but, as seen above, that raises the same error. I did specify a
> > secondary port in the XProc with:
> >
> > <p:output port="secondary" sequence="true"/>
> >
> > but that seems to have no effect on the outcome (perhaps I specified it
> > in the wrong place?). I think I should be able to write multiple result
> > documents, and that I have misunderstood something about how to set that
> > up. For what it's worth, I also think I may need a <p:store> step to
> > save the multiple result documents, and although I've used <p:store>
> > successfully with single outputs, I don't know what it should look like
> > to save a set of result documents. But if I've understood the error
> > correctly, I'm stalled on the XSLT step, and need to get past that first.
> >
> > 2. As an alternative to <xsl:for-each-group> inside the XSLT stylesheet,
> > I considered doing the grouping in XProc, but I don't see anything
> > within XProc comparable to <xsl:for-each-group>. If I am reading the
> > description correctly, a <p:for-each> step might let me loop over <item>
> > elements, but it does not appear to have the ability to form the <item>
> > elements into groups according to shared @paradigm values and loop over
> > those groups. I could run an XSLT pre-processing step to do the
> > grouping, all within our document, creating an intermediate hierarchical
> > level (called, say, <group>) and then use <p:for-each> to loop over
> > those, but that extra step feels to me like a hack, that is, as if there
> > should be a more direct way to do what I need. Should I ignore that
> feeling?
> >
> > Assuming I can get the individual result documents written to disk, I
> > think I can do the subsequent transformation with a <p:for-each> step.
> >
> > I am using MorganaXProc-IIIse 0.9.4.2-beta and Saxon EE 10.0, and
> > running from the command line under MacOS 10.15.7. Thanks in advance for
> > any pointers in The Right Direction.
> >
> > Best,
> >
> > David
> > djbpitt@gmail.com <mailto:djbpitt@gmail.com>
> >
> >
> >
>
> --
> Gerrit Imsieke
> Geschäftsführer / Managing Director
> le-tex publishing services GmbH
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>
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