XProc Minutes 25 May 2006

See http://www.w3.org/XML/XProc/2006/05/25-minutes.html

W3C[1]

                                   - DRAFT -

                            XML Processing Model WG

Meeting 22, 25 May 2006

   Agenda[2]

   See also: IRC log[3]

Attendees

   Present
           Norm, Mohamed, Alessandro, Paul, Richard, Henry, Andrew, Alex

   Regrets
           Michael, Rui

   Chair
           Norm

   Scribe
           Norm

Contents

     * Topics
         1. Accept this agenda?
         2. Accept minutes from the previous teleconference?
         3. Next meeting: 1 June telcon
         4. Face-to-face: 2-4 Aug 2006.
         5. Mini "Technical Plenary" in January?
         6. Review of open action items
         7. XProc syntax
         8. Any other business?
     * Summary of Action Items

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

  Accept this agenda?

   -> http://www.w3.org/XML/XProc/2006/05/25-agenda.html

   Accepted.

  Accept minutes from the previous teleconference?

   -> http://www.w3.org/XML/XProc/2006/05/18-minutes.html

   Accepted.

  Next meeting: 1 June telcon

   Any regrets?

   None given.

  Face-to-face: 2-4 Aug 2006.

   -> http://www.w3.org/2002/09/wbs/38398/XProcFTF2/

   -> http://www.w3.org/XML/XProc/2006/08/02-04-f2f.html

  Mini "Technical Plenary" in January?

   Norm proposes that we don't need to meet in January since we will have met
   in August.

   We'll revisit if it actually happens, it's still just in the planning
   stages today.

  Review of open action items

   1. A-13-01: MSM to draft a complete table; ETA: 15 June 2006

   <scribe> Continued.

  XProc syntax

   Email threads:

   ->
   http://lists.w3.org/Archives/Public/public-xml-processing-model-wg/2006May/0087.html

   ->
   http://lists.w3.org/Archives/Public/public-xml-processing-model-wg/2006May/0072.html

   ->
   http://lists.w3.org/Archives/Public/public-xml-processing-model-wg/2006May/0041.html

   ->
   http://lists.w3.org/Archives/Public/public-xml-processing-model-wg/2006May/0039.html

   Norm opens the floor for discussion.

   Alex: Can you provide a synopis?

   Norm mumbles a bit

   We seem to be reaching consensus on the non-directed syntax as our first
   WD syntax

   Henry: You mean the generic syntax, right? Names like p:process and
   p:input and p:output.

   Yes.

   Variables/parameters/inputs/outputs share a single symbol space

   Parameters are strings

   References in one direction, which Norm describes badly

   Richard: I'd been thinking that outputs defined labels and input referred
   to them

   Some discussion, poorly recorded by the hapless scribe

   The outstanding issue is XPath references to input documents

   Can an XPath expression refer to multiple in-scope input documents? Or
   only to a single document.

   Alessandro: We also seem to have consensus on p:input/p:with-input, etc.

   Richard: If all the inputs are available as documents that you can refer
   to by name in XPath expressions, this results in a hidden dependency
   within XPaths.
   ... In order to determine which components have to have been evaulated,
   you have to peek into the XPath to see what inputs it relies on.
   ... That seems to be a minor implementation annoyance but a good way of
   hiding dependencies.
   ... which is a bad thing.
   ... It means that two things in apparently unrelated branches of the
   pipeline may have to wait for each other because of the XPath expression
   one uses.
   ... It really is just a syntax issue on one level in that you could draw
   all the lines in explicitly. It's just that it's burried deep down in the
   syntax.

   <MoZ> could we uses a "uses=" attributes

   Alex: Are we assuming that the variables and parameters share the same
   symbol space.
   ... If they share the same symbol space, then there are conversion issues.
   What happens if you attempt to select a node from a string?

   Richard: I think the issue of strings is a red herring. Though I agree
   that we should restrict them to strings now, that doesn't mean we can't
   make them more complex in the future.
   ... If the functionality that's needed is the ability to refer to multiple
   documents, it could be done more explicitly. There could be a syntax that
   bound variables to the names of outputs of other steps. That at least
   would make it expicit which ones were being used.

   Mohamed: The idea (uses= from before) is to make it explicit. If they are
   defined on other points in the document, then maybe they are not visually
   explicit even if they're technically explicit.

   Alex: In XSLT, variables and parameters can be bound to a variety of
   things and that's useful. The typing issues come into play. I might want
   to bind inputs to parameters, for example.

   Norm: That comes back to the point earlier about parameters being strings.

   Richard: I agree that it would be nice to go beyond strings for
   parameters, but we can stick with strings for now.

   Alex: Do we need this distinction of variables and parameters?

   Richard: I don't think we've agreed that there are any variables yet.

   Alex describes his p:let proposal

   Richard: Is this different in any way from a sub-pipeline?

   Alex: No, not really. The distinction between variables and parameters
   seems just not useful to me.
   ... You need to be able to manipulate parameters just like you can
   manipulate inputs and outputs in the pipeline
   ... Let provides a scope
   ... Let is also hierarchical, it has inputs and outputs.

   Richard: It seems to me that the advantage isn't the scoping as such, put
   a place to do some calculation on some existing parameters to get a new
   one.

   Alex: If you're calculating a parameter with an input, you need to know
   what its dependent on.

   <MoZ> for me let is a class definition

   Alex: I'm quite happy if it can be done as a sub-pipeline, but I don't
   want to have to call out to some other file.

   Norm: I don't think we've discussed that at all.

   Alex: This could easily be some variation of a sub-pipeline call.

   Richard: In lisp, let is implemented as a macro. It expands into a lambda
   that's passed some parameters.
   ... We've been saying that a let in our pipeline might be equivalent to a
   sub-pipeline and provides a place to bind some new input parameters.
   ... It would be nice if this were really true and if you could say that
   let was equivalent to this pipeline construct.

   <MoZ> +1 for using few keywords in Xproc (for p:let to become a
   p:subpipeline or rich-subpipeline)

   Richard: I hadn't imagined that sub-pipelines would be transparent, so let
   would bind to a sub-pipeline with the right declarations for inputs and
   outputs.

   Norm: I see.
   ... Let's try to come back around to XPaths over input documents.
   ... I have reservations about the refer-to-inputs-as-variables style and
   Richard has given some good technical reasons why it makes analysis
   harder. Does anyone want to argue in favor of it?

   No one speaks.

   <MoZ> using namespaces "io:foo" and "p:foo"

   <MoZ> will this be a solution ?

   Alex: What if we had parameter bindings as children of the p:input?

   <scribe> ACTION A-22-01: Norm to record the open issue about what an XPath
   expression over a document sequence means [recorded in
   http://www.w3.org/2006/05/25-xproc-minutes.html#action01[12]]

   Proposal: XPath expressions will be evaluated over exactly one input,
   syntactic details unresolved.

   Alessandro: I think it's hard to record a consensus on that because Jeni
   isn't here.
   ... Personally, this is what we've implemented, so I kind of like XPath
   expressions evaluated over a single document.

   Norm: I'll postpone the question for a week.

   Norm expresses a desire to have a completed first WD before the f2f.

  Any other business?

   None.

   Adjourned.

Summary of Action Items

   [NEW] ACTION: Norm to record the open issue about what an XPath expression
   over a document sequence means [recorded in
   http://www.w3.org/2006/05/25-xproc-minutes.html#action01[13]]
   **
   [End of minutes]

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   [1] http://www.w3.org/
   [2] http://www.w3.org/XML/XProc/2006/05/25-agenda.html
   [3] http://www.w3.org/2006/05/25-xproc-irc
   [12] http://www.w3.org/2006/05/25-xproc-minutes.html#action01
   [13] http://www.w3.org/2006/05/25-xproc-minutes.html#action01
   [14] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/scribedoc.htm
   [15] http://dev.w3.org/cvsweb/2002/scribe/
   [16] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/
   [17] http://www.w3.org/XML/XProc/2006/05/25-agenda.html
   [18] http://www.w3.org/2006/05/25-xproc-minutes.html

    Minutes formatted by David Booth's scribe.perl[14] version 1.127 (CVS
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    $Date: 2006/05/25 16:28:04 $

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