XOM API for Processing XML with Java

[Elliotte Rusty Harold <elharo AT ibiblio.org>]

If you can boil this down to a simple example that doesn't use the
actual data that would be even better. What I need is the bare minimum
to show:

1. What you expect to happen.
2. What is happening.

>From that I can determine if this is a bug or WAI.




On Sun, May 5, 2019 at 6:54 AM Axel von Engel <a.vonengel AT gmail.com> wrote:
>
> Thanks for the quick response. I tried to keep the initial mail short, but
> apparently that was too short ;)
>
> I'll prepare a repo with an example, but it will take me a couple of days
> at least. I might not be able to show the XSL Transformation error I
> mentioned, though. I can't publish the involved stylesheets without
> approval from the company, and that will probably take ages.
>
> Am Sa., 4. Mai 2019 um 01:10 Uhr schrieb Elliotte Rusty Harold <
> elharo AT ibiblio.org>:
>
> > Interesting. It's hard to follow all that without an example though so
> > I'm not sure whether XOM is doing something wrong or what. If you
> > could bundle this into a self-contained example, or best of all, a
> > unit test, I could take a look.
> >
> > On Fri, May 3, 2019 at 3:44 PM Axel von Engel <a.vonengel AT gmail.com>
> > wrote:
> > >
> > > Hi everyone,
> > >
> > > (This got a bit long, see last paragraph for TL;DR)
> > >
> > > I recently started to work on migrating a DocBook toolchain to a Gradle
> > > plugin, and was looking into doing all the transformations via SAX in
> > Java.
> > > The pre-existing toolchain at the company uses a variety of pre- and
> > > post-processing XSL stylesheets, and even used different processors for
> > > those.
> > >
> > > My first approach was the following:
> > > 1. Parse the source via Xerces
> > > 2. Construct a TransformerHandler backed by Saxon for each of the
> > > stylesheets
> > > 3. Use a FOP renderer as the final SAX ContentHandler to create PDF
> > output
> > >
> > > This worked pretty well, until I ran into this lovely Xerces issue:
> > > https://issues.apache.org/jira/browse/XERCESJ-1102
> > > So basically, nested xi:include tags result in wrong xml:base 
> > > attributes,
> > > leading to wrong relative image paths.
> > >
> > > Through some searching, I found XOM, and used that on top of Xerces:
> > >
> > > SAXParserFactory parserFactory =
> > >
> > SAXParserFactory.newInstance("org.apache.xerces.jaxp.SAXParserFactoryImpl",
> > > classloader);
> > > // disable xInclude on the Xerces parser
> > > parserFactory.setXIncludeAware(false);
> > > // more config ...
> > > XMLReader xmlReader = parserFactory.newSAXParser().getXMLReader();
> > >
> > > Builder parser = new Builder(xmlReader);
> > > Document input = parser.build(rootDocbookFile);
> > >
> > > input = XIncluder.resolve(input, parser);
> > >
> > > // handler creation omitted:
> > > SAXConverter saxConverter = new SAXConverter(handler);
> > > saxConverter.convert(input);
> > >
> > > The problem with this approach: the SAXConverter does not emit xml:base
> > > attributes. I later found this in the sources:
> > >
> > https://github.com/elharo/xom/blob/master/src/nu/xom/converters/SAXConverter.java#L98
> > > Which led to my current workaround hack: Use reflection to set
> > > SAXConverter.stripBaseAttributes = true
> > >
> > > Another approach I tried was to use XOM to do the XSL transformations
> > > instead of using the SAX API. This resulted in some errors that said
> > > something like "can't insert Text into Document" without any meaningful
> > > hints at which XSL template might have caused it, so I didn't 
> > > investigate
> > > further.
> > >
> > > All in all, I feel this is a hack, and find it hard to believe there is
> > no
> > > cleaner solution. Google and Stackoverflow didn't turn up much else,
> > though.
> > >
> > > TL;DR: My root issue is with Xerces: it can't properly resolve nested
> > > xi:include tags.
> > > Does someone know another solution to parse the XML, and resolve the
> > > xi:include tags correctly?
> > > Is there some way to debug what causes XOM to error during XSLT?
> > > Or maybe there is another way to get the results from XOM to the SAX API
> > > (including xml:base attributes, and without writing to disk)?
> > >
> > > Best regards
> > > Axel von Engel
> > > _______________________________________________
> > > XOM-interest mailing list
> > > XOM-interest AT lists.ibiblio.org
> > > https://lists.ibiblio.org/mailman/listinfo/xom-interest
> >
> >
> >
> > --
> > Elliotte Rusty Harold
> > elharo AT ibiblio.org
> > _______________________________________________
> > XOM-interest mailing list
> > XOM-interest AT lists.ibiblio.org
> > https://lists.ibiblio.org/mailman/listinfo/xom-interest
> >
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-- 
Elliotte Rusty Harold
elharo AT ibiblio.org