- From: Norman Walsh <Norman.Walsh@Sun.COM>
- Date: Thu, 18 May 2006 12:04:43 -0400
- To: public-xml-processing-model-wg@w3.org
- Message-ID: <87ves3tj38.fsf@nwalsh.com>
See http://www.w3.org/XML/XProc/2006/05/18-minutes.html
W3C[1]
- DRAFT -
XML Processing Model WG
Meeting 21, 18 May 2006
Agenda[2]
See also: IRC log[3]
Attendees
Present
Norm, Murray, Paul, Alessandro, Richard, Alex, Rui
Regrets
Andrew, Michael, Henry
Chair
Norm
Scribe
Norm
Contents
* Topics
1. Accept this agenda?
2. Accept minutes from the previous teleconference?
3. Next meeting: 25 May telcon
4. Face-to-face: 2-4 Aug 2006.
5. Review of open action items
6. Issue 3089: What version/subset of XPath is used in conditionals?
7. Any other business?
* Summary of Action Items
----------------------------------------------------------------------
Accept this agenda?
-> http://www.w3.org/XML/XProc/2006/05/18-agenda.html
Accepted.
Accept minutes from the previous teleconference?
-> http://www.w3.org/XML/XProc/2006/04/11-minutes.html
Accepted.
Next meeting: 25 May telcon
Any regrets?
Rui sends regrets (WWW 2006)
Face-to-face: 2-4 Aug 2006.
Please register and review the local arrangements pages.
-> http://www.w3.org/2002/09/wbs/38398/XProcFTF2/
Review of open action items
A-20-01: Norm to write up his thoughts on parameters and inputs
<scribe> Completed.
A-19-01: Alex to send mail describing his ideas about variables.
<scribe> Completed.
A-13-01: MSM to draft a complete table; ETA: 15 June 2006
<scribe> Continued.
Issue 3089: What version/subset of XPath is used in conditionals?
-> http://www.w3.org/Bugs/Public/show_bug.cgi?id=3089
Norm has given reasons for perferring XPath 1.0.
Others have pushed back.
Murray: Is XPath 2.0 backwards compatible with 1.0?
Norm: Sort of.
<richard> http://www.w3.org/TR/xpath20/#id-backwards-compatibility[8]
Richard: Some expressions have different meanings.
Murray: I'm torn. I tend to agree that if we use XPath 2.0, we're ahead of
the vangaurd and will lose people. Compatibility mode will make it too
complex.
... If we straight-out adopt XPath 2.0, then maybe we've gone too far.
... I don't have a strong opinion technically, but can we do it
politically?
... I was working under the assumption that 2.0 is backwards compatible. I
was going to suggest that in our first draft, we make a statement to say
that we've chosen 1.0 for the following reasons, however, we stipulate
that it's possible that 2.0 is the way to go, we need feedback.
Norm repeats some of his arguments.
Richard: I agree, and if there's an XSLT 2. component, you can use that.
... The excess verbosity in the small number of cases where it's needed
doesn't seem a hardship
Mohamed: I think the smaller subset is XPath 2.0 in compatibility mode. In
XPath 1.0 there are some additional things.
... The case of saying that XProc can handle XPath 2.0 in compatibility
mode can be maybe the point of consensus.
Richard: XPath 2.0 in 1.0 compatibility mode doesn't remove all the extra
stuff in 2.0
Alessandro: Maybe we could say that implementations have a choice of using
XPath 1.0 or XPath 2.0 in compatibility mode.
... If you want to write a pipeline that works on any implementation, then
you have to use XPath 1.0
Norm reiterates his concern about interoperability.
<MoZ> (XPath2.0 in compatibility mode) intersect (XPath 1.0)
Murray points out that anyone can write a component to use XPath 2.0
expressions
Richard: If "if" and maybe one or two other places were the only places
where XPath expressions entered into things, then maybe you could do it
with different components.
... But we also want to use XPath to establish parameters
Murray: In the pipeline language, we'll have expressions like p:if and
we're trying to decide where to get the expression language
... We get to point into another spec and avoid writing all the
explanations.
... The second part is, I need to use something that's in XPath 2.0. I can
do that with an XSLT 2.0 component and return something into the pipeline
(that can be tested with XPath 1.0)
<MoZ> XSLT1.0 and XSLT2.0 are compnonents
<MoZ> not XPath1.0 and XPath2.0
Alessandro: Just like in the language we have steps that use components
and we plan to have a number of components specified in the language, we
could have the same approach for expressions.
<MoZ> XPath will be a part of XProc language, but XSLT2 will be a
component of the language
Alex: I think the problem is that the places I want to go with XPath 2.0
are type-based and that would require a whole new layer to our language.
That would create a whole new bunch of work and significantly delay our
progress. As much as I want 2.0, I don't think we should try to do all
that in V1.0.
... The most conservative thing to do is say it's XPath 1.0 and see what
users say when we put out the first draft.
... I don't believe XPath 2.0 is the 20% (the edge case), but I don't
think we should take it on unless we're willing to take on schema typing.
Norm: Would we have consensus to proceed in the following way: we publish
the first draft saying that the expressions in the language are XPath 1.0
(and only 1.0) with an explicit request for users feedback on whether or
not that's satisfactory for enough of their use cases.
Mohamed: I just want to add that on some platforms there will be XPath 2.0
available before XPath 1.0.
Norm: I think it would be reasonable to allow an implementor to use a 2.0
processor in 1.0 backwards-compatibility mode.
Alessandro: I still feel that maybe we want to discuss this further. A
question: I am wondering if we say that we use XPath 1.0 now, how will we
use 2.0 in the future.
Norm: I expect to use the version of the pipeline doucment for that
purpose.
Richard: Restricting it to the subset with 1.0 compatibility mode does
have an advantage. It would be straightforward to say that V2
implementations that choose to be able to run 1.0 pipelines will run them
in backwards compatibility mode. That maximizes the chances that they'll
still work.
Mohamed: I was thinking that this was the restriction of compatibility
mode. Maybe we have to be more restrictive and say that it's not in
compatibility mode.
Norm: I think we'd lose interoperability if we did that.
Alessandro: One question that hasn't been adressed very clearly: would it
be allowed for a pipeline implementation to use an XPath 2 engine in
backwards compatibility mode. Would that be considered compliant?
Richard: I don't see why not.
Norm: I think that's the right thing to do.
Alessandro: If we say either a 1.0 engine or a 2.0 engine in backwards
compatiblity mode then I can agree with the consensus.
Paul: So we're saying that the core language will use 1.0 and any language
that does the right thing is ok.
Richard: We'd be explicitly allowing the variance of 2.0 backwards
incompatibility.
Some discussion of what we're going to say about errors.
<MoZ> we could give a parser with xproc
Richard wonders if processors can detect the edge cases that give
different answers with 2.0 in backwards compatibility mode.
Richard enumerates the cases. Case 2 is nearly impossible to detect.
Alex: I think that a good XPath 2.0 library will tell you if you're in one
of these strange cases.
Mohamed: Maybe we could handle this a different way, by asking the XSL WG
to handle these differences as warnings.
... Maybe as warnings, it could be handled by the implementors. Those
warnings may give errors in XProc.
Norm: I doubt it.
Proposal: We say that we use XPath 1.0 expressions (in the first draft,
with an explicit request for user feedback). Expressions that aren't valid
XPath 1.0 expressions are errors. An implementation that evaluates the
expressions using an XPath 2.0 processor in backwards compatibility mode
is conformant.
(Provided that it gives errors for non-1.0 expressions)
Alex: Do we want to include the number case?
Richard: I'd be entirely happy if we said that implmentations should
report the compatibility mode cases.
Accepted.
<PGrosso> "Should" is okay for compat issues, but "must" for non-1.0
expressions.
<richard> I agree
<alexmilowski> I agree too. :)
<MoZ> +1 to PGrosso
Any other business?
None.
Adjourned
Summary of Action Items
[End of minutes]
----------------------------------------------------------------------
[1] http://www.w3.org/
[2] http://www.w3.org/XML/XProc/2006/05/18-agenda.html
[3] http://www.w3.org/2006/05/18-xproc-irc
[8] http://www.w3.org/TR/xpath20/#id-backwards-compatibility
[9] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/scribedoc.htm
[10] http://dev.w3.org/cvsweb/2002/scribe/
Minutes formatted by David Booth's scribe.perl[9] version 1.127 (CVS
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$Date: 2006/05/18 16:03:00 $
Received on Thursday, 18 May 2006 16:05:13 UTC