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XProc Minutes 15 Nov 2007

From: Norman Walsh <ndw@nwalsh.com>
Date: Thu, 15 Nov 2007 12:08:40 -0500
To: public-xml-processing-model-wg@w3.org
Message-ID: <m28x4zbfmv.fsf@nwalsh.com>
See http://www.w3.org/XML/XProc/2007/11/15-minutes


                                   - DRAFT -

                            XML Processing Model WG

15 Nov 2007


   See also: IRC log[3]


           Norm, Alessandro, Richard, Henry, Rui, Andrew, Murray, Alex

           Paul, Mohamed (partial)




     * Topics
         1. Accept this agenda?
         2. Accept minutes from the previous meeting?
         3. Next meeting: telcon 29 November 2007
         4. XPath versions
         5. XSLT versions
         6. New public working draft
         7. New step types (p:hash, p:uuid, p:www-form-url(en|de)code
         8. Other last call comments (implicit inputs/outputs; default
         9. Any other business
     * Summary of Action Items


  Accept this agenda?

   -> http://www.w3.org/XML/XProc/2007/11/15-agenda


  Accept minutes from the previous meeting?



  Next meeting: telcon 29 November 2007

   Alessandro gives regrets for 29 Nov

   (Note that we are not meeting on 22 Nov!)

  XPath versions


   Norm summarizes the state of play

   Henry: The traditional schema group compromise seems appropriate: call
   attention to it in the next draft of the spec and ask for implementor and
   user feedback.


   Alex: So we're going to allow for different answers in the two versions.

   Norm: Yes, for now, with Henry's suggestion for priority feedback

   Henry: The 99.99% case is when you're comparing strings in XPath 1, one of
   the strings will coerce to a number. In that case, you will get the same

   Murray: Why can't we settle on XPath 2.0

   Henry/Richard: Because right now there are too many implementation
   communities where 1.0 is only available.

   Murray: I think it'd be better to leave them behind than to possibly give
   different results.

   Henry: The proposal as it stands includes the idea that we give authors
   guidance for interoperability.
   ... It's extremely unlikely that the kinds of xpaths that don't
   interoperate will really turn up in practice.
   ... I'd rather include the XPath 1.0 people in at the expense of that very
   small problem than exclude them to get rid of it.

   Alex: Interoperability is more than just getting the same answer; there
   are also cases where the XPaths simply won't work on some implementations.

   Norm: I think saying XPath 2.0 only would be a tactical error.

   Murray: So can we say 1.0 only?

   Norm: There are implementors that only plan to support 2.0.

   Alex: I'm not sure that guiding authors to use some squishy middle ground
   is the right answer.
   ... I think it'd be better to explain the interoperability problems.

   Some discussion of the right interoperability story.

   Henry: I'd like to see the editor try to write up the point that we
   arrived at.

   Norm: Uh, I did that.

   Alex: Do we want to allow the xpath-version attribute on any element?

   Norm: I was thinking of cut-and-paste
   ... But I'm perfectly happy to try putting it only on p:pipeline-library
   and p:pipeline

   Some discussion of what the differences between 1.0 and 2.0 actually are

   Richard: Should we just make it a static error to attempt to use XPath 2.0
   with an XPath 1.0-only processor?

   Henry: I'm happy with the silent attempt because it is amenable to
   conditional pipelines.

   Murray: Back in the days when we were first talking about SGML on the web,
   one of the expressions that came up was "perverse obscurity".
   ... This discussion of 1.0/2.0 corners is perverse obscurity.
   ... We're setting up a situation where it is possible for pipelines to
   generate the wrong answer.

   Henry: I think you're exhagerating the situation.

   Norm: I think the number of cases where you're going to give the wrong
   answer is quite small.

   Richard: Presumably users of XSLT 2.0 processors with XSLT 1.0 stylesheets
   are experiencing the same problems.

   Norm: yes.

   Henry: I've been doing this for years and I've never had a problem.

   Norm: We could make XPath 1.0 compatibility mode a MUST for implementors

   Richard: And we could say that XPath 1.0 implemntors MUST only run
   expressions that will give teh same result

   Norm: Bah, I don't think I want to go there.

   Henry: I sort of like this road; nobody loses, it's just that some people
   win more than others.
   ... I think the spec should say that if someone asks for XPath 2.0
   evaluation, your XPath 1.0 implementation MUST only evaluate those XPaths
   which they know have the same value.

   Richard: And if yours doesn't know any, it must reject them all.

   Norm: So we're going basically the route I outlined, but saying that 2.0
   processor must implement 1.0 mode and a 1.0 processor must not evaluate
   any expression that it cannot determine will give the same result in XPath

   Richard: Can we find out what the subset is?

   Alex: Maybe. There's an appendix in XPath 2.0 spec.

   Proposed: Go forward as above for the next draft.


  XSLT versions


   Norm outlines his plan

   Alex: I'm all for it.

   Proposed: go this way for the next draft.


  New public working draft

   Norm: I think we need a new draft asap.

   Richard: We also need the stuff about what types are in scope.

   Norm: I'm happy to do the next draft with a fair number of "TBD" sections.

   Proposed: editor will make a new public draft with the XPath/XSLT
   decisions and as many other decisions as possible to be published as soon
   as practical.


  New step types (p:hash, p:uuid, p:www-form-url(en|de)code

   Norm: Anyone object to putting those in the next draft?

   Mohamed, do we have strong use cases for them

   Norm: Yes, and they're optional anyway


  Other last call comments (implicit inputs/outputs; default bindings)


   Norm summarizes the state of default bindings


   Norm attempts to summarize the default input/output case.

   See 2.3 in the 13 Nov editor's draft.


   <scribe> ACTION: Norm to change all the examples [recorded in

  Any other business

   Henry: It occurs to me that wrt the visible step types, it's not
   completely clear whether we have schema rules or xslt rules. If I import
   something that imports something else, do I get to use what's in the third
   thing or not.
   ... Richard and my prose supposes that the answer is yes. The current
   draft suggests that it's no.
   ... And the message about circular imports clearly suggests that it's no.

   Richard: I believe that Henry's message is right, modulo that fix.

   Henry: I'd like to particularly encourage Alex to review it.

   Alex: Right. Will do.


Summary of Action Items

   [NEW] ACTION: Norm to change all the examples [recorded in
   [End of minutes]


   [1] http://www.w3.org/
   [2] http://www.w3.org/XML/XProc/2007/11/15-agenda
   [3] http://www.w3.org/2007/11/15-xproc-irc
   [10] http://www.w3.org/2007/11/15-xproc-minutes.html#action01
   [11] http://www.w3.org/2007/11/15-xproc-minutes.html#action01
   [12] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/scribedoc.htm
   [13] http://dev.w3.org/cvsweb/2002/scribe/

    Minutes formatted by David Booth's scribe.perl[12] version 1.128 (CVS
    $Date: 2007/11/15 17:07:31 $

Received on Thursday, 15 November 2007 17:08:55 UTC

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