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Minutes for XProc WG telcon of 16 Feb 2006

From: Norman Walsh <Norman.Walsh@Sun.COM>
Date: Thu, 16 Feb 2006 12:17:35 -0500
To: public-xml-processing-model-wg@w3.org
Message-ID: <87oe17kyts.fsf@nwalsh.com>
See also: http://www.w3.org/XML/XProc/2006/02/16-minutes.html

                                  - DRAFT -

                            XML Processing Model WG

16 Feb 2006


   See also: IRC log[3]


           Vikas, Norm, Alessandro, Rui, Murray, Paul, Alex, Richard, Andrew,

           Michael_Sperberg-McQueen, Henry, Jeni




     * Topics
         1. Administrivia
         2. Accept this agenda?
         3. Accept minutes from the previous teleconference?
         4. Next meeting: 23 Feb 2006.
         5. Dail-in for the face-to-face at the plenary?
         6. Agenda planning for the face-to-face
         7. Requirements and Use Cases
         8. Any other business?
     * Summary of Action Items



  Accept this agenda?

   -> http://www.w3.org/XML/XProc/2006/02/16-agenda.html[4]


  Accept minutes from the previous teleconference?

   -> http://www.w3.org/XML/XProc/2006/02/09-minutes.html[5]


  Next meeting: 23 Feb 2006.

   Any regrets?


  Dail-in for the face-to-face at the plenary?

   (08:00+01:00-18:00+01:00 Monday and Tuesday, 27-28 Feb)

   Andrew would like to call in.

  Agenda planning for the face-to-face

   Alex: Infosets/representation of inputs as a topic for the f2f

   Norm: Processing model

   Richard: I was speaking about the non-xml stuff being the same thing

   Alex: Does it make sense to spend some time talking about the various
   tools that are out there?

   Richard: I was going to suggest the attendees that have a pipeline
   implementation give a brief presentation on it.

  Requirements and Use Cases


   <PGrosso> The above URL is from Alessandro.

   <PGrosso> Alex: Point 1 is to have a defn of parameters which we do now.

   <PGrosso> Alex: Point 2 should be taken care of now too. Alessandro

   <PGrosso> Alex: Point 3 (standard names for steps). We discussed that a
   component is like "XSLT" but a step is a thing in the pipeline that may
   make use of a given component like XSLT.

   Richard: Is a step a component plus some parameters plus it's position in
   the pipeline?

   Alex: Yes. In fact a step might even use multiple components.

   Richard: We probably don't have to come to complete closure on this now

   Alessandro: My comment was narrower, just that in the particular place in
   4.6 where the word "step" is used, the word "component" would have been
   ... I see a Step like a function call and a Component more like a

   Alex: I could change 4.6 to say Component and be happy with that

   General agreement

   Alex: Point 4 is intended to say that we won't create a pipeline
   vocabulary that can't be validated

   Richard: Can you give an example of something that couldn't be validated?

   Alex: Atom, for example, voilates the XML Schema UPA rule by allowing
   interleaving at several levels
   ... I would like to avoid that, I'd like to create a vocabulary that can
   be validated with either language

   Richard: I agree as long as it's not taken to extremes. Don't use things
   that many validation tools can't validate. But if we wind up with
   co-constraints (in attribute values, for example), it may never the less
   be the best way to do that.
   ... We can't rule out all constraints that can't be checked by an XML
   Schema validator.
   ... This sounds more like a design principle

   Norm: I agree with Richard.

   Alex: Ok.

   Alessandro: I was thinking of the XSLT case, where there are good things
   that can't be validated easily with XML schema. I wouldn't like us to
   constrian ourselves not to do that.

   Murray: On the other hand, we'd like processing languages to be as easily
   validated as possible. We should think long and hard before we let this
   one go.
   ... If we're going to allow something that isn't validatable, we're going
   to think long and hard about it.

   Alex: Point 5 is about naming of pipelines
   ... There's no use case for many of the things in the document so that's a
   more general problem.

   Norm: Can you give an example?

   Alex discusses giving pipeline documents URIs

   Murray: The mechanism that's missing is do I have a way to reference a
   pipeline and have it invoked

   Richard: Do you mean in general or in a pipeline?
   ... Do we want pipelines to be able to refer to one another?

   Alex: Consider 4.9 on composition, you could say use XInclude
   ... I think naming goes along with composition.

   Richard: It's been the case in several specifications that the new
   language has defined it's own inclusion mechansim. It has always been a
   hope that XInclude was vailable it wouldn't be necessary. Often, alas, it
   turns out to be necessary.

   Norm: I think the design principle "reuse existing technologies" covers
   that case.
   ... I propose that we leave 4.9 and let naming fall out of our composition
   mechanism if it does

   Richard: We also have the case of supplying the pipeline in the URI so
   that you can write a URI that means run this pipeline on this document
   with these parameters.

   Norm: I can't tell from 4.10 if that is what was for.

   Consensus: delete 4.10


   <PGrosso> [Norm's email]

   Thank you, Paul

   Norm describes his ideas

   Alex asks about the syntax

   Some discussion of flow and parallelism

   Richard: I have some problems that are simpler than Alex's case.
   ... The use of a "current" infoset has two implications: straight through
   processing, everything is one input or output unless it's named; the other
   is that it implies sequential processing.
   ... I don't think the sequential processing is an issue. But the first one
   is more important.
   ... If we want to have some components like "XML diff" then I don't think
   we want to have the two inputs be described in entirely different ways.
   ... Maybe one has to be input1 and the other input2, but we shouldn't have
   to go deeper than that.
   ... but using names for the non-XML data, then I think that's an approache
   to consider.

   A collection?

   Richard: that isn't what I had in mind
   ... Suppose you have a pipeline that wants to cleanup some insignificant
   diffs and then run the XML diff component.
   ... I imagine that you might start this pipeline with two inputs and at
   some point they get merged.
   ... At the point of the execution of the step that does the diff, I want
   that to be just like the case where there's only one

   Murray: I'm confused.

   Alex: Conceptually, this is two pipes inside a pipe I think.

   Some discussion of a shell script case

   Richard: I'm assuming that we have a way to have two things in the
   pipeline, I want to get them merged later one
   ... The way we get two things into the pipeline is by having some upstream
   thing refer to URIs

   Erik: I think it's an oversimplification to use the shell script analogy
   for everything.
   ... There are existing pipeline languages that can already handle this

   Murray: Where I'm having difficulty is the case where there's more than
   one stdin

   Richard: That's only if we only allow stdin on a process.

   Murray: If we allow each step to have stdin/stdout, that step can also
   have other inputs.

   Richard: Unix actually has a whole bunch of file descriptors, 0, 1, 2, and
   with sufficient hackery, you can actually read from 5 without ever giving
   it a name.

   Alex: We need a white board for this.

   Norm asks for concrete examples

   Nearly out of time

  Any other business?



Summary of Action Items

   [End of minutes]


   [1] http://www.w3.org/
   [2] http://www.w3.org/XML/XProc/2006/02/16-agenda.html
   [3] http://www.w3.org/2006/02/16-xproc-irc
   [4] http://www.w3.org/XML/XProc/2006/02/16-agenda.html
   [5] http://www.w3.org/XML/XProc/2006/02/09-minutes.html
   [6] http://lists.w3.org/Archives/Public/public-xml-processing-model-wg/2006Feb/0013.html
   [7] http://lists.w3.org/Archives/Public/public-xml-processing-model-wg/2006Feb/0032.html
   [8] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/scribedoc.htm
   [9] http://dev.w3.org/cvsweb/2002/scribe/

    Minutes formatted by David Booth's scribe.perl[8] version 1.127 (CVS
    $Date: 2006/02/16 17:15:30 $

                                        Be seeing you,

Norman.Walsh@Sun.COM / XML Standards Architect / Sun Microsystems, Inc.
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Received on Thursday, 16 February 2006 17:17:57 UTC

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