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XProc Minutes 24 Apr 2008

From: Norman Walsh <ndw@nwalsh.com>
Date: Thu, 24 Apr 2008 15:59:35 -0400
To: public-xml-processing-model-wg@w3.org
Message-ID: <m2d4ofrplk.fsf@nwalsh.com>
See http://www.w3.org/XML/XProc/2008/04/24-minutes

W3C[1]

                                   - DRAFT -

                            XML Processing Model WG

Meeting 109, 24 Apr 2008

   Agenda[2]

   See also: IRC log[3]

Attendees

   Present
           Norm, Vojtech, Paul, Richard, Alex, Andrew, Michael_[xx:13]

   Regrets
           Alessandro, Rui

   Chair
           Norm

   Scribe
           Norm

Contents

     * Topics
         1. Accept this agenda?
         2. Accept minutes from the previous meeting?
         3. Next meeting: telcon 1 May 2008?
         4. Consideration of the proposed next working draft.
         5. Default context for options and variables
         6. p:declare-step/p:import in p:declare-step (for atomic steps)
         7. Exclude prefixes on p:inline
         8. What happens when @xpath-versions are mixed.
         9. Any other business?
     * Summary of Action Items

     ----------------------------------------------------------------------

  Accept this agenda?

   -> http://www.w3.org/XML/XProc/2008/04/24-agenda

   Norm: I'd like to add this morning's email threads

  Accept minutes from the previous meeting?

   -> http://www.w3.org/XML/XProc/2008/04/17-minutes

   Accepted.

  Next meeting: telcon 1 May 2008?

   Vojtech gives regrets.

  Consideration of the proposed next working draft.

   -> http://www.w3.org/XML/XProc/docs/langspec.html

   No questions or comments.

   Henry will provide updated DTDs and W3C XML Schemas before 1 May.

  Default context for options and variables

   Norm attempts to summarize

   Norm: We could allow a sequence, but on balance I'd rather not.

   ->
   http://www.w3.org/mid/546c6c1c0804230152q5b9eccc0ta1737307cc143e32@mail.gmail.com

   Norm: If we leave it an error now, we can always make it not an error
   later.
   ... Does anyone want to argue for a change?

   None heard, the status quo prevails.

  p:declare-step/p:import in p:declare-step (for atomic steps)

   Norm summarizes.

   -> http://www.w3.org/mid/m24p9rv5jq.fsf@nwalsh.com

   Henry: Sounds right to me

   Proposed: Make the changes Norm suggests.

   Accepted.

  Exclude prefixes on p:inline

   -> http://www.w3.org/mid/f5bmynjnz1v.fsf@hildegard.inf.ed.ac.uk

   Henry: It's a shameless lift from XSLT 2.0, very lightly edited.
   ... If we haven't changed our minds about doing this, the only thing that
   really requires peoples attention is the inventory of namespaces
   ... whcih are excluded by definition. I chose to exclude the two that
   might actually appear at the top-level in a pipeline.
   ... I excldued the error namespace and the instance prefix, because I
   don't think those are going to occur.

   Norm: I don't think the .../xproc/1.0 "namespace" is every going to be
   bound.

   <MSM> What if my pipeline is creating a pipeline?

   Norm is confused about stripping the namespace.

   Henry: If you want to use the namespace, you can add it back in another
   step.
   ... Eliminates any namespace on every node on the tree.

   Alex: But it gets put *back in* by namespace fixup.

   Henry: Yeah, I guess that works.

   Norm: Bah. Do we really need to do this?

   Alex: I think it's a very good idea. There are lots of situations where if
   you want to inline something, having a namespace declaration could be bad
   for the end result. There are environments where extra namespaces mean
   different things. IE freaks out on HTML with namespace declarations, for
   example.
   ... It may be an edge case, but it's a crucial edge case.

   <MSM> [I don't understand Henry's argument that you MUST remove it
   everywhere. Why not just say the child of p:inline doesn't inherit any of
   the specified bindings, so that if it rebinds them they will be there.

   Henry: When you need it, you really need it.

   Alex: And I think it's easy to describe.
   ... Getting p:inline right is real work.

   Michael: Why do you have to remove them everywhere?

   Henry: There's no gaurantee that the datamodel that you have is
   efficiently implemented. So removing an in-scope namespace from my parent
   doesn't remove it from me.

   Michael: You have to recompute them, but I think it's a mistake to confuse
   information with APIs.

   Henry: It appears to only remove it in one place, but that's because if
   you have a literal XML fragment in your XSLT stylesheet, the removal
   applies to all of them.

   Some discussion of the XSLT case.

   Richard: The XSLT case is copying nodes from the stylesheet to the result.
   So they aren't copied.

   Henry: Right, so it's the same for us. Up until this point, there was no
   necessity to copy and now there is.

   Some discussion of whether nodes that are 'eq' to each other can get
   passed to different steps.

   Richard: I wonder if there's a whole can of worms unaddressed here.

   Henry: I think anyone who uses any kind of stateful data model doesn't
   have a problem here.

   Richard: Suppose you ahve a sequence and the thing you do is count the
   union of the nodes in the sequence.

   Henry: We need to have this in the test suite.

   Richard: The excluding of namespaces seems to amount to a "when
   necessary".

   Norm: Anyone against doing this?

   None heard.

   Michael: I think being able to trim namespace declarations is extremely
   useful. This seems unnecessarily complicated.
   ... I agree that XSLT 2.0 does exactly the same thing. Maybe Alex is right
   that namespace fixup saves it for those of us who use one of the excluded
   namespaces.
   ... Do we have the same sort of namespace fixup rules?

   Norm: Yes.

   Richard: The case where namespace prefix doesn't work is when the prefix
   is used in content. Because then it isn't noticed.
   ... Namespace fixup won't gaurantee that you get the right prefix.

   Norm: True.

   Vojtech: I think the prefixes are the author's responsibility.

   Richard: But the excluded namespaces will remove the bindings.

   Vojtech: If the XProc namespace is removed automatically, that's a
   problem. But if you remove the prefix, that's your problem.

   Richard: That's not the way it works in XSLT. You specify it with a
   prefix, but it suppresses the namespace nodes that that prefix maps to.

   Henry: So, worst case, you need to use a namespace-rename step.

   Proposed: We adopt Henry's proposal for the 1 May draft.

   Accepted.

  What happens when @xpath-versions are mixed.

   Norm: Attempts to summarize from
   http://www.w3.org/mid/546c6c1c0804232256p71ee6e0dke3008132c75ff58a@mail.gmail.com[10]
   ... We allow @name, @psvi-required and @xpath-version on the decl. of
   atomic steps.
   ... I think they're mostly harmless on atomic steps andw es houldn't worry
   abou tit.
   ... What do we want to say about mixed @xpath-versions across calls?
   ... I think the obvious answers are either, ignore the nested ones or its
   an error.

   Consider:

   <p:pipeline xpath-version="2.0">

   <p:declare-step type="ex:foo" xpath-version="1.0"/>

   <ex:foo/>

   </p:pipeline>

   Vojtech: The default is 1.0 so what happens with the base steps.

   Norm: That's a good point.
   ... I don't think we can expect implementations to do both.

   Henry: The problem is in libraries.

   Norm: I think we need to say that an unspecified version is license to use
   whatever you want and mixing them is a dynamic error.

   Henry: How do we avoid screwing users unnecessarily. And simultaneiously
   avoid giving them weird results.

   Norm: Uhm...

   Henry: What we want is late binding.

   Vojtech: If the implementation is prepared to switch, then it should work.

   Norm muses

   Vojtech: I think the default now is 1.0.

   Norm: Static analysis should always show what versions could be used, so
   maybe late binding is possible.

   <scribe> ACTION: Norm to propose how @xpath-version should deal with mixed
   versions. [recorded in
   http://www.w3.org/2008/04/24-xproc-minutes.html#action01[11]]

  Any other business?

   None heard.

   Adjourned.

Summary of Action Items

   [NEW] ACTION: Norm to propose how @xpath-version should deal with mixed
   versions. [recorded in
   http://www.w3.org/2008/04/24-xproc-minutes.html#action01[12]]
    
   [End of minutes]

     ----------------------------------------------------------------------

   [1] http://www.w3.org/
   [2] http://www.w3.org/XML/XProc/2008/04/24-agenda
   [3] http://www.w3.org/2008/04/24-xproc-irc
   [10] http://www.w3.org/mid/546c6c1c0804232256p71ee6e0dke3008132c75ff58a@mail.gmail.com
   [11] http://www.w3.org/2008/04/24-xproc-minutes.html#action01
   [12] http://www.w3.org/2008/04/24-xproc-minutes.html#action01
   [13] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/scribedoc.htm
   [14] http://dev.w3.org/cvsweb/2002/scribe/

    Minutes formatted by David Booth's scribe.perl[13] version 1.133 (CVS
    log[14])
    $Date: 2008/04/24 19:58:34 $

Received on Thursday, 24 April 2008 20:00:19 GMT

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