First impressions, xproc

Been meaning to send this for a while, sorry. I'm slowly forgetting things I found hard.

When I started using XProc I found some things difficult to understand, based mostly on the spec...

. relationship between options, parameters, attributes

. what the heck p:pipe does... I for a while decided it causes the pipe you
  name to run, and it wasn't clear what would happen if you had two p:pipes with
  the same name, would the step run once or twice?
  This isn't actually correct, it seems every _connected_ step runs, and unconnected
  steps (e.g. imported from a library) don't unless you connect them. But it wasn't
  clear from the spec. There seem to be multiple uses of p:pipe and not examples
  of all of the different uses.

. how to get errors and xsl:message's from XSLT and from p:exec

. how to re-use the same step output as input for two or more other steps (this
  one was really basic, but there's no p:parallel step...)

. why one would want p:pipeline instead of p:declare-step

I found out lots of things, as usual for learning from specs, from examples, which would have been easier if I'd found more examples (admittedly Norm's site was down at the time). For example, it took me a day or two to work out that XSLT 2 result-document doesn't work in XProc -- the XSLT step returns a sequence of documents and you have to save them yourself.

Still haven't found an easy way to run Antenna House CSS Formatter with cx:css-formatter in Calabash in Oxygen - I got it working by renaming a class file and setting 30 or so environment variables copied from Antenna House "" but that didn't seem to be a benefit over p:exec really. I expect this'll improve if cx:css-formatter becomes p:css-formatter, but overall pipelines seem really hard to debug and trace.

Once they work, they keep on working, which is good.

Sorry these notes ended up being short -- I had a longer version and lost it. But I already suggested to Norm the single biggest thing I'd like, which is considerably more introductory text in each section :)



Liam Quin - XML Activity Lead, W3C,
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Received on Tuesday, 11 November 2014 05:52:29 UTC