W3C

- DRAFT -

Forms Working Group Teleconference

25 Sep 2013

Agenda

See also: IRC log

Attendees

Present
ebruchez, Steven, [IPcaller], nvdbleek, unl
Regrets
Chair
Steven
Scribe
Steven

Contents


<trackbot> Date: 25 September 2013

<nvdbleek> I'm calling in a minute

<unl> zakim doesn't like me...

http://www.balisage.net/Proceedings/vol10/html/Pemberton01/BalisageVol10-Pemberton01.html

Checking if an extension function exists and implementation/version

sniffing

http://lists.w3.org/Archives/Public/public-xformsusers/2013Sep/0000.html

sniffing

http://lists.w3.org/Archives/Public/public-xformsusers/2013Sep/0000.html

Steven: Maybe replace the exception with an error?

Erik: I had an action item to report on our error handling
... for instance an xpath expression error just halts the processor
... we don't dispatch binding-exception nor compute-exception

<ebruchez> http://www.w3.org/2012/02/15-forms-minutes.html#action02

<ebruchez> <trackbot> Created ACTION-1868 - Bruchez to summarize problems with error handling and three options for variable type handling.

action-1868?

<trackbot> action-1868 -- Erik Bruchez to Bruchez to summarize problems with error handling and three options for variable type handling. -- due 2012-02-22 -- OPEN

<trackbot> https://www.w3.org/2005/06/tracker/xforms/actions/1868

Erik: There are two areas where you might want to catch errors: xpath exprs and actions
... having an answer to that might help this problem
... we might also have a way to test for a function

Steven: If you had a way of testing, how might you alter the form's behaviour? What's the use case?

<nvdbleek> http://www.w3.org/TR/xslt-30/#func-function-available

Erik: His use case is for testing implementations

<nvdbleek> This is the XSLT 3.0 function to test if a function is available

Erik: We could just import that function.

<ebruchez> http://www.w3.org/TR/xpath-functions-30/#func-function-lookup

Erik: That example uses the fact that XPath 3 has functions as returnable values

<nvdbleek> erik: This is not possible in XPath 2.0

Erik: function-available is in XSLT, not XPath

<nvdbleek> http://www.w3.org/TR/xslt20/#function-function-available

Erik: so it is in XSLT 2
... So we could import the xslt 2 function with the same signature and behavior

Steven: Do we think it's worth doing?

Erik: It is valuable.
... but maybe we should check with Eric. It looks like it could help.

Steven: Or make the exception an error.

<nvdbleek> http://www.w3.org/TR/xslt-30/#element-try

Erik: That would be rather heavy to use.
... In our implementation we change the error events a bit comapred with the spec.
... I would be happy to send a suggestion for changes.

Steven: If we made bad decisions in the past with error events, we should fix them.

Erik: Eric agreed that we should try to fix the problem areas in a chat I had with him

Steven: What are we going to do?

Erik: 1) reply to him and mention the choices 2) make errors recoverable 3) import the XSLT function

Nick: the error handling is going to be a challenge, and a lot of work
... for actions it is easy, but not for bindings.

Steven: it doesn't sound like we can fix error handling before last call.

Erik: I can send a message on how we do it, and what impact it would have

Steven: Please do, that is action-1868

Erik: I can answer Eric's message

<scribe> ACTION: Erik to answer Eric vd Vlist's message on identifying available functions [recorded in http://www.w3.org/2013/09/25-forms-minutes.html#action01]

<trackbot> Created ACTION-1956 - Answer eric vd vlist's message on identifying available functions [on Erik Bruchez - due 2013-10-02].

Editorial: fixed a few consistency issues with "XML Schema" and

code markup

http://lists.w3.org/Archives/Public/public-forms/2013Sep/0003.html

Steven: Looks OK.

ACTION-1955 - Write text for type information for xpath expressions

http://lists.w3.org/Archives/Public/public-forms/2013Sep/0004.html

<ebruchez> http://www.w3.org/MarkUp/Forms/wiki/XForms_2.0#Typed_Values

Erik: Although the expression language is a separate module, there is a core xpath element in the language
... it leaves space for other expression languages, but it is hard to know what another language might require, so hard to say anything concrete about it.
... Expressions needs access to types.
... We have three ways to add type information (bind, xsi: and schema)
... but some off-the-shelf schema validators don't annotate values in some cases
... This means that we need text that says "may" for those cases.
... so it is unclear if we *can* mandate the types being available in all cases
... but this text covers built-in types that are always available.
... I listed all types that *must* be provided
... an XPath processor doesn't know about the xforms variants of the xsd basic types
... so the data model must provide the xsd type to the xpath processor
... And the last part, which is what happens if the expression doesn't match the type, an error case
... a run-time error
... that can be recovered from
... so this defines what happens there
... the result is an empty string
... and then we consider that constraints fail.
... or it is as if the expression hasn't run.

Steven: Does an event get proagated?

Erik: There is no event for that, the only one that we have stops processing.

Steven: So we do need one, so that you can catch the error
... So how to take this further?

Erik: I already have an action item for the error handling.

AOB

Steven: Can I ask you Nick to summarise for next week where we are in respect of getting to LC?

Nick: OK.

s;s/Erik:/Erik:/G;;

Summary of Action Items

[NEW] ACTION: Erik to answer Eric vd Vlist's message on identifying available functions [recorded in http://www.w3.org/2013/09/25-forms-minutes.html#action01]
 
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No ScribeNick specified.  Guessing ScribeNick: Steven
Inferring Scribes: Steven
Default Present: ebruchez, Steven, [IPcaller], nvdbleek, unl
Present: ebruchez Steven [IPcaller] nvdbleek unl
Agenda: http://lists.w3.org/Archives/Public/public-forms/2013Sep/0005
Found Date: 25 Sep 2013
Guessing minutes URL: http://www.w3.org/2013/09/25-forms-minutes.html
People with action items: erik

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