W3C

- DRAFT -

XML Processing Model WG

17 Jan 2013

Agenda

See also: IRC log

Attendees

Present
Norm, Mohamed, Jim, Alex, Vojtech, Henry
Regrets
Chair
Norm
Scribe
Norm

Contents


<MoZ> http://edition.cnn.com/2013/01/16/world/europe/uk-helicopter-crash/index.html

Accept this agenda?

-> http://www.w3.org/XML/XProc/2013/01/17-agenda

Accepted.

Accept minutes from the previous meeting?

-> http://www.w3.org/XML/XProc/2012/11/01-minutes

Accepted.

Next meeting: 24 Jan 2013

No regrets

Change meeting time?

Jim: I'm finding Thursday challenging.

Norm: Time of day is to suit west coast USA and Europe.
... I don't like Monday's for meetings. I could do Tue, Wed, or, reluctantly, Friday.

Jim: Maybe Cornelia would be able to make it if we moved the meeting time?

Alex: Henry has a complicated schedule too.

<scribe> ACTION: Norm to send email polling for a different/better meeting time. [recorded in http://www.w3.org/2013/01/17-xproc-minutes.html#action01]

Review of open action items

Norm: Alex, Henry, Norm, please report on your actions in email; suggest which ones are overtaken by events.

<jfuller_> zip and unzip ... still draft

<jfuller_> http://www.w3.org/XML/XProc/docs/xproc-zip_unzip.html

Alex: What's the status on the Processing Model document?

Norm: The status is we're in Last Call and have comments from reviewers that we haven't addressed.

Henry summarizes.

Alex: Does it make sense to try to bring this to closure as fast as possible, even if other stuff is more interesting.

Norm: Yes, that's the case.

-> http://lists.w3.org/Archives/Public/public-xml-processing-model-comments/2012Jan/0000.html

Alex: I'll try to look at this after the call today.

<scribe> ACTION: Norm to make XML Processor Profiles document an explicit agenda item [recorded in http://www.w3.org/2013/01/17-xproc-minutes.html#action02]

Review progress on use cases/requirements

<jfuller_> http://www.w3.org/XML/XProc/docs/requirements-v2-jim.xml

Norm: Jim, I think you said you'd take a stab at it.

Jim: I worked on the zip/unzip step instead. I did do some work, but it's not uploaded yet.
... The link above has notes from our f2f meeting. I'll try to get a revised document online by Tuesday for next week.

Review of proposal to simplify parameters

Norm: I think we were talking about Vojtech's inheritence proposal.

Vojtech: The main idea was that maybe we could get rid of parameters altogether by inventing some sort of inheritence mechanism.
... Because we don't want to lose the "magical" behavior that they inherit from the pipeline.
... So options could possibly inherit from the calling context or maybe the other way around.
... This option "propagates down" if it's used. From a nested scope, for example.

<jfuller_> initial Norm link on fixing parameters - http://lists.w3.org/Archives/Public/public-xml-processing-model-wg/2012Sep/0014.html

Vojtech: It would be different to our current parameters but it would allow for things like having an XSLT step that has an option called parameters that's declared that it inherits from above. And by some kind of naming convention you could actually still use this magic that you're used to.
... The main idea would be to get rid of parameters concept alltogether and replace it with options.
... And with maps, the "parameters" option could be a map and those key/values could be inherited.

Alex: Presumably we'd still need the with-param kind of construct.

<jfuller_> last meeting minute param discussion - http://www.w3.org/XML/XProc/2012/11/01-minutes.html#item04

Vojtech: That's a question. Or some way to extend or override the map options.

Alex: I think you could make that work in a number of ways. With-param could just be on the XSLT step.
... You could have a default parameter option and with-param could just modify the map associated with the default parameter option. We could support an option name.

Vojtech: We'd have to be really careful with with-param and with-option and the order that we evaluate these things in. You could have with-option dynamically building the map and with-param updating it.
... That whole inheritence mechanism is simpler but also introduces some complexity, some side-effects that could be surprising if you don't really know what you're doing.

Alex: Are you imagining the inheritence goes by the data-flow or by the structure?

Vojtech: On the declare-option you'd say inherit=true and then when you use the XSLT step, if the parameters option is not set, it would look in the upper-contexts to find an option or variable with the same name and use that value.
... You could also do it the other way around, on a pipeline you can declare an option called parameters and inherit=true and it could propogate down.

Norm: That's the same functionality, it's just a case of where you put the label, right?

Vojtech: Well, yes, perhaps, but I think it's safer in some sense to propogate down because the author has more control. The other way around, using the steps could introduce surprises.

Alex: Minus a whole bunch of details, I like this idea. I never liked the distinction between options and parameters. I didn't want to do it, but we didn't have an alternative.
... So I like this approach, but we need to make sure we get the details right.

Vojtech: In my idea, it's all based on the option names.
... Any option name could be inherited.

Alex: We need to decide if inheritence is a special thing that you turn on, or it's the default and you have a way to turn it off.

Jim: I'd go for always inherited.

Vojtech: If it's always turned on, it could help with unbound optional options.

Alex: I think I'm in favor of always inheriting too.

Norm: It only applies to steps inside compound steps so it's not too dangerous, I guess.

Vojtech: If you really want something to be unbound, you should be able to make it explicit.

Norm: But we don't have a syntax for that.

Alex: But we'd need one, I think.
... We need to look at the details.

Vojtech: I'm willing to dive a little deeper.

Norm: I think that would be great.

Henry: I'd like to see the same examples, if at all possible.

Vojtech: The same?

Henry: The same ones that Norm used in his proposal.

Vojtech: Ok.

<alexmilowski> LOL

Henry: I'm confident that either one of these or almost anything else would be an improvement.

Support for document metadata?

Norm attempts to summarize.

Henry: We had this in the old markup pipeline engine, and the motivation in that case was output type. You could allow internal XSLT steps to set output type HTML and have that actually work at the end of the pipeline because it got passed along with the metadata.
... The bad news is that you have to think through the semantics about what kind of steps preserve this and what kind don't. It's not at all obvious, for example, that an XSLT step preserves the metadata. It may not make sense for the metadata to propagate.
... That may just be too hard a question to answer.

Alex: It may also be the case that the pipeline author wants control over that.

Henry: But we don't want them to have to think about that if they don't want to.

Alex: But like inheritence, it might be the case that there needs to be a default and a way to specify the alternative.
... Output content type is a good example.
... I'm a little confused, because we had at least two proposals and then the f2f, and I'm not sure where we've gotten to.

Norm attempts to explain again: we started with Vojtech's proposal for binary which required passing along the MIME type and we generalized that to document metadata.

Alex: Right, but my proposal didn't require that.

The chair expresses some confusion about the state of the binary proposals.

<scribe> ACTION: Norm to put review of the binary proposals on the agenda for next week [recorded in http://www.w3.org/2013/01/17-xproc-minutes.html#action03]

Alex: Two things in my proposal are that XML is the only thing that flows through the pipeline. The binary is identified by reference. Everything is treated uniformly. It doesn't matter if the resource manager has a magic URI or if you point off into the ether of the universe

Norm: Ok, my bad.

Alex: I'd like to see some good use cases for document metadata.

Norm: Fair enough.

Henry: The other one that I recall that we recall that we used this for is preserving the character encoding. Which I can't remember if you can get from the infoset or not.

Alex: There's a whole bunch of things that can be grouped into: how I got the original data vs. parameters needed for serialization. There's a whole bunch of metadata in there that's related. People might want to preserve how they read the data in how they write it and metadata is a good way to transport that form one place to another.

Henry: The reason we did this for character encoding is that we invented an encoding that allowed us to preserve entity references.

Vojtech: I have a question: all the metadata values or attributes that you mentioned look like magic metadata fields. But applications can also set things, like timestamps and labels, yes?

Henry: Oh, absolutely, pipeline authors could come up with their own metadata.

Jim: For non-XML it allows us to add metadata without changing the documents. It's like implementing a state machine without having the state in the documents.

<scribe> ACTION: Norm to make sure document metadata stays on the agenda [recorded in http://www.w3.org/2013/01/17-xproc-minutes.html#action04]

Any other business?

Alex: Who's going to XML Prague

Jim: Everyone but Henry

<scribe> ACTION: Jim/WG to discuss XProcathon at next telcon [recorded in http://www.w3.org/2013/01/17-xproc-minutes.html#action05]

Adjourned.

Date: 17 Jan 2013

<scribe> Meeting: 224

<scribe> Scribe: Norm

<scribe> ScribeNick: norm

Summary of Action Items

[NEW] ACTION: Jim/WG to discuss XProcathon at next telcon [recorded in http://www.w3.org/2013/01/17-xproc-minutes.html#action05]
[NEW] ACTION: Norm to make sure document metadata stays on the agenda [recorded in http://www.w3.org/2013/01/17-xproc-minutes.html#action04]
[NEW] ACTION: Norm to make XML Processor Profiles document an explicit agenda item [recorded in http://www.w3.org/2013/01/17-xproc-minutes.html#action02]
[NEW] ACTION: Norm to put review of the binary proposals on the agenda for next week [recorded in http://www.w3.org/2013/01/17-xproc-minutes.html#action03]
[NEW] ACTION: Norm to send email polling for a different/better meeting time. [recorded in http://www.w3.org/2013/01/17-xproc-minutes.html#action01]
 
[End of minutes]

Minutes formatted by David Booth's scribe.perl version 1.137 (CVS log)
$Date: 2013-01-17 16:01:05 $

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This is scribe.perl Revision: 1.137  of Date: 2012/09/20 20:19:01  
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Guessing input format: RRSAgent_Text_Format (score 1.00)

Succeeded: s/TIme/Time/
Succeeded: s/that!/that if they don't want to./
Found Scribe: Norm
Inferring ScribeNick: Norm
Found ScribeNick: norm
Default Present: +420.6.026.9.aaaa, Alex_Milows, Norm, Moz, jfuller, Vojtech, ht
Present: Norm Mohamed Jim Alex Vojtech Henry
Agenda: http://www.w3.org/XML/XProc/2013/01/17-agenda
Found Date: 17 Jan 2013
Guessing minutes URL: http://www.w3.org/2013/01/17-xproc-minutes.html
People with action items: jim norm wg

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