IRC log of xproc on 2006-06-01

Timestamps are in UTC.

14:52:08 [RRSAgent]
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logging to
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14:53:29 [Alessandro]
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14:53:52 [Norm]
Meeting: XML Processing Model WG
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Scribe: Norm
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ScribeNick: Norm
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Date: 1 Jun 2006
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Chair: Norm
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14:55:56 [PGrosso]
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14:56:45 [MoZ]
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14:57:16 [MoZ]
Zakim, what is the code?
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sorry, MoZ, I don't know what conference this is
14:57:39 [MoZ]
Zakim, this will be xproc
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ok, MoZ; I see XML_PMWG()11:00AM scheduled to start in 3 minutes
14:57:46 [MoZ]
Zakim, what is the code?
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the conference code is 97762 (tel:+1.617.761.6200), MoZ
14:58:25 [Zakim]
XML_PMWG()11:00AM has now started
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14:59:14 [rlopes]
zakim, [ip is Rui
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+Rui; got it
14:59:19 [Zakim]
15:00:04 [Zakim]
15:00:36 [ht]
zakim, please call ht-781
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ok, ht; the call is being made
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15:01:23 [richard]
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zakim, ? is richard
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+richard; got it
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zakim, ? is AndrewF
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+AndrewF; got it
15:44:59 [PGrosso]
15:45:54 [MoZ]
to slow ...:(
15:46:08 [MoZ]
thx paul
15:59:57 [Zakim]
15:59:58 [Zakim]
15:59:58 [Zakim]
15:59:59 [Zakim]
16:00:01 [Zakim]
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XML_PMWG()11:00AM has ended
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Attendees were Norm, moz, [IPcaller], Rui, Alessandro_Vernet, PGrosso, Ht, richard, AndrewF
16:00:34 [MoZ]
Zakim, who is on the phone?
16:00:34 [Zakim]
apparently XML_PMWG()11:00AM has ended, MoZ
16:00:35 [Zakim]
On IRC I see richard, MoZ, Alessandro, RRSAgent, Zakim, MSM, ht
16:06:01 [Norm]
Norm has joined #xproc
16:06:32 [Norm]
Presents: Norm, Mohamed, Rui, Alessando, Paul, Henry, Richard, Andrew
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Regrets: Murray, Michael
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Topic: Accept this agenda?
16:06:32 [Norm]
16:06:32 [Norm]
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Topic: Accept minutes from the previous teleconference?
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16:06:38 [Norm]
16:06:40 [Norm]
Topic: Next meeting: 8 June telcon
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Any regrets?
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None given.
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Topic: Face-to-face: 2-4 Aug 2006.
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Topic: Review of open action items
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1. A-22-01: Norm to create an issue to track xpath expressions over a sequence of documents
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Completed: Issue #3306
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2. A-13-01: MSM to draft a complete table; ETA: 15 June 2006
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16:06:58 [Norm]
Topic: Continuation of our syntax discussion
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Richard: Can you summarize where we are wrt syntax?
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Norm tries
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Rui: There was one point when we said that variables can contain strings only.
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But that didn't seem to be a point of consensus. Jeni was about to make the
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content a nodeset, for example.
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Richard: Should we attempt to agree a version 0 where we say "no we're
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not having any of those" and then see where we get.
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Norm: That seems reasonable to me. Do you have a proposal?
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Richard: No, we don't have variables. We just have inputs, outputs,
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parameters. Parameters are strings. There's no scoping mechanism. Then
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we can discuss which things we add. This isn't what the spec will say,
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but it will help us get some things out of the way.
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Norm: A concrete syntax for this?
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Richard: Yes. Then we could have some implementations of it.
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Norm: I really want to know where XPath expressions fit in.
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Richard: I was going to suggest no XPath at all, parameters are
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constant strings.
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... Then discussions of XPaths will involve proposals to change that
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existing syntax.
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Norm: What do others think about this approach?
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Paul: I'm always for simplification.
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Alessandro: If we do that, will we have to back-track if we want to go
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to a syntax that allowed XPath.
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Richard: Maybe.
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Alessandro: So maybe we want to make a decision early on about XPath.
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Henry: As long as we don't let this out into the wild too much, or we all
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solemnly swear that backward incompatibilities with this syntax won't have
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any impact on our future decisions, I think it'd be ok. I don't think it's
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a mistake.
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Richard: I was not suggesting that any version 0 would exist for any
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purpose other than to help us consider what version 1 should be.
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Alternatively, if you think that's too simple, can we enumerate now
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which things we need to decide before we do a version zero.
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Norm expresses that it was XPaths that were this feature in his personal
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Mohamed: I think that the way Jeni is exploring the use of XPath for
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conditionals is useful research. But the fear I have is that at the
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moment the XPath using is augmenting the power of XPath by adding new
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functions. For example, count on sequences. Some of this are extremely
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needed. We have to focus on the problem of speaking about sequences of
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documents and how we handle this type.
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Norm: I propose that XPath over a sequence is an error.
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Richard: You can do it in XPath 1.0 (using union of document()s for example).
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These are separable. If the contexts were always given by a pipe going into
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the component, then if the sequence was a sequence you'd get a context
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nodeset consisting of those nodes.
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Mohamed: But if you do $a|$b, you lose the order. It's a set. Maybe we
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have to say that it's a set and not a sequence.
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Norm: I still think we might get away with calling it an error.
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Richard: You can certainly work around it with other standard components
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if we made it an error.
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Norm: Yes, you can certainly work around it.
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Richard: And a future version could allow them.
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Norm, carrying Jeni's proxy, attempts to argue for Jeni's position
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that we should allow the variable syntax reference to documents.
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Some discussion of how much work it is to analyze the expressions.
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Doesn't really require a full XPath parser, but does require care with
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quoted strings.
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Richard: Use of variables there would suggest that that's how they should
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be used everywhere.
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Norm: I'm not sure I want arbitrary XPath expressions in ref=.
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Richard: If what you say is a document is ref="$name", then you're
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saying that the value of ref is an XPath referring to a document.
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Then you might expect to say ref="document('http://...')".
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Alessandro: XPath doesn't have a document() function, that's from XSLT.
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Richard: It would also lead people to believe that you could just use
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part of the output with ref="$foo/something".
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Norm: I think we'd have to say that ref is a bare label or that ref is
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a single variable reference. Either way we violate the principle of
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least surprise, but I'm not sure what else we can do.
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Richard: I'm happy to go with the variable reference mechanism if
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that's what the group wants, but I'm not enthusiastic about it. How
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about a straw poll?
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Norm: Straw poll: documents by variable reference syntax, or some other
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syntax that limits XPath expressions to a single document. Is that clear?
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(Not really)
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Richard: Within XPath expressions, documents as dollar variables?
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Richard: To clarify, saying "yes" is supporting what Jeni wants, right?
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Henry: I'm not sure I understand the implications. Can we look at some
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Alessandro: Jeni's relevant message is titled "How should variables be set?"
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Richard: (Reading the mail) Option A: XPath expressions are evaluated
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over a single document. Option B: Expressions are evaluated with no
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context node, variables are used to refer to intermediate documents.
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(Paraphrased by the scribe who has no connectivity at the moment.)
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Henry: I don't like either of these, I think this is the wrong level.
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Is this meant to be the syntax that users write? This pushes aspect of
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the low-level syntax into the XPath in ways I don't like at all. We've
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said repeatedly that for simple straight-through pipelines, we
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shouldn't require authors to know the names of any inputs and outputs.
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If we achieve that goal, then none of these approaches will work
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because they require you to know the names of things.
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Norm: Don't you think the simple case is that there are no xpath
16:10:32 [Norm]
16:10:34 [Norm]
Henry: I should be able to use XPaths without having to add any other
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mechanism. I think the 90% case for using XPaths will be to refer to
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the only document that there is in any given step. I don't see that as
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falling out of either of these proposals.
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ACTION: Henry to describe an alternate proposal in email.
16:10:46 [Norm]
Richard: Have we considered the following: XPath's can't refer to any
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documents except the documents that are input to the steps. It can
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refer to those by name.
16:10:52 [Norm]
Norm: We haven't considered that before, but I do like it.
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Rui: If we do this, then we'll have steps with lots of inputs.
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We'll have to pass all the documents we want to refer to as inputs.
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This will make dependency analysis harder.
16:11:00 [Norm]
Richard: I don't understand. I'm expecting most of my steps not to have
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any XPaths at all. Most of the ones that do are going to refer to a single
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document. The case where there are multiple documents in a single XPath
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seems like an edge case.
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Rui: I think that they'll be used in conditionals and in debugging
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parameters. If you close the domain of the access of the variable to
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only what's in the input, you'll have to give a lot of inputs.
16:11:16 [Norm]
Richard: You were thinking of pipeline variables that you could set to
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these things. I was only thinking of this to deal with documents, not
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with constants.
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Norm: I don't think the straw poll would be valuable, does anyone?
16:11:24 [Norm]
Paul: No, but we need actions if we're going to make progress.
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Norm: Richard would you take an action to write a syntax proposal?
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Richard: Yes.
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ACTION: Richard to write a syntax proposal.
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ACTION: Norm to write a syntax proposal.
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Topic: Any other business?
16:11:36 [Norm]
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rrsagent, pointer
16:11:38 [RRSAgent]
16:13:44 [Norm]
rrsagent, make logs world-visbile
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rrsagent, make logs world-visible
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rrsagent, draft minutes
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I have made the request to generate Norm