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Re: Problem with XForms 1.0 Basic Profile document when used with XFo rms Full processor

From: Steven Pemberton <steven.pemberton@cwi.nl>
Date: Tue, 02 May 2006 16:25:50 +0200
To: "Klotz, Leigh" <Leigh.Klotz@pahv.xerox.com>, "'www-forms-editor@w3.org'" <www-forms-editor@w3.org>
Message-ID: <op.s8xg1cdrsmjzpq@acer3010.lan>

Leigh,

Thank you for your comment.

The XForms WG discussed this issue[1] and resolved that the problem lay  
with the description of how types are bound to the data in XForms. They  
resolved to:

"Issue an erratum for 6.1.1 Type property about how the type is bound to  
the data. It mustn't be done by equivalency to xsi:type attribute."

If this reply satisfies your comment, please reply to this mail to that  
effect.

Many thanks,

Steven Pemberton
For the XForms WG

[1] http://www.w3.org/2006/03/23-xforms-minutes#item02

On Tue, 31 Aug 2004 23:23:56 +0200, Klotz, Leigh  
<Leigh.Klotz@pahv.xerox.com> wrote:

>
>
> In "3 Conformance", the XForms 1.0 Basic Profile CR [1] says
>   XForms Basic Profile processors may implement a subset of an XML Schema
> processor
>   [XML Schema part 1], [XML Schema part 2], requiring only what is  
> necessary
> to process
>   the attribute xsi:type on instance data for simpleTypes only and the  
> type
> model
>   item property for simpleTypes only.
>
> In "3.3.1 The model Element", the XForms 1.0 REC [2] says
>   Optional list of xsd:anyURI links to XML Schema documents outside this
> model element.
>   The XForms Processor must process all Schemas listed in this attribute.
>
> My understanding is that the Basic Profile changes this "must" to either  
> a
> "must not" or perhaps a "should not" for XForms Basic.
> In any case, I assume that the schema attribute (and similarly, the  
> embedded
> xsd:schema element) are allowed in documents processed by an XForms Basic
> processor, but are to be ignored.
>
> Now, consider the following case where an instance contains an element  
> with
> a simple value (such as a decimal or a time) and a boolean attribute:
>
>   <time precise="true">06:00:00</time>
>
> The goal of adding an attribute to an element of simple type content is
> common, and in fact the first qustion in a popular XML Schema FAQ [3]  
> shows
> that it is in fact, a frequently-asked question.  The cited FAQ then  
> gives a
> complexType definition extending a simple type and adding an attribute.
>
> Here is a complete XForms Full example, using XML Schema, a sample  
> instance
> document, and an XHTML 1 document with XForms controls, using the XML
> Schema.  It relies on the XML Schema referred to from the model to define
> the type of the attribute as boolean, so that the XForms Processor may
> display it as a checkbox.
>
> XForms Basic does not interpret the schema attribute, but it does  
> "process
> ... type model item property for simpleTypes only" so we can add
>   <xf:bind ref="my:length/@my:precise" type="xsd:boolean" />
> to the model, and both Full and Basic XForms Processors will display the
> attribute as a boolean (for example, as a checkbox in a graphical user
> interface).
>
> Note that the base type of the element, xsd:time, is also one that XForms
> processors may choose to use for display purposes, perhaps by showing a  
> time
> chooser (see "8.1.2 The Input Element" [4]).  So, the natural next step
> would be to bind that type to the node, as follows:
>   <xf:bind ref="my:length" type="xsd:time" />
> This will indeed work in XForms Basic, because it will process the type
> model item property, and xsd:time is an XML Schema simpleType and is in  
> the
> list of types to be processed by XForms Basic.
>
> Unfortunately, XForms Full processors have already interpreted the XML
> Schema specified by the model schema attribute, and have a conflicting  
> type.
>
> Therefore, I believe that it is difficult to create XForms Full profile
> documents that also work in XForms Basic, unless some subtyping  
> allowances
> are introduced into the consistency checking performed by the type model
> item property.
>
> Leigh.
>
> -------------------precision.xml---------------------
>   <?xml version="1.0" ?>
>   <data xmlns="http://www.example.com">
>     <time precise="true">06:00:00</time>
>   </data>
> ---------------------precision.xsd-----------------------
>   <?xml version="1.0" ?>
>   <xsd:schema xmlns:my="http://www.example.com"
> 	      targetNamespace="http://www.example.com"
> 	      xmlns:xsd="http://www.w3.org/2001/XMLSchema"
> 	      elementFormDefault="qualified">
>     <xsd:element name="data">
>       <xsd:complexType>
> 	<xsd:sequence>
> 	  <xsd:element ref="my:time" />
> 	</xsd:sequence>
>       </xsd:complexType>
>     </xsd:element>
>     <xsd:element name="time" type="my:preciseTime"/>
>     <xsd:complexType name="preciseTime">
>       <xsd:simpleContent>
> 	<xsd:extension base="xsd:time">
> 	  <xsd:attribute name="precise" type="xsd:boolean" use="required"/>
> 	</xsd:extension>
>       </xsd:simpleContent>
>     </xsd:complexType>
>   </xsd:schema>
>
> ---------------------precision.xhtml---------------------
>   <?xml version="1.0" encoding="iso-8859-1" ?>
>   <html xmlns="http://www.w3.org/1999/xhtml"
> 	xmlns:xf="http://www.w3.org/2002/xforms"
> 	xmlns:xsd="http://www.w3.org/2001/XMLSchema"
> 	xmlns:my="http://www.example.com">
>     <head>
>       <title>XForms Samples</title>
>       <xf:model schema="precision.xsd">
> 	<xf:instance src="precision.xml" />
> 	<xf:bind nodeset="my:time" type="xsd:time" />
> 	<xf:bind nodeset="my:time/@my:precise" type="xsd:boolean" />
>       </xf:model>
>     </head>
>     <body>
>       <h1>Precision</h1>
>       <xf:group>
> 	<xf:input ref="my:time"><xf:label>Time</xf:label></xf:input>
> 	<xf:input
> ref="my:time/@my:precise"><xf:label>Precise?</xf:label></xf:input>
>       </xf:group>
>     </body>
>   </html>
> -------------------------------------------------------------
>
> [1] http://www.w3.org/TR/2003/CR-xforms-basic-20031014/#id2606183
> [2]
> http://www.w3.org/TR/2003/REC-xforms-20031014/index-all.html#structure-model
> [3] http://www.mathling.com/xsd/
> [4] http://www.w3.org/TR/2003/REC-xforms-20031014/index-all.html#ui-input
>
>
Received on Tuesday, 2 May 2006 14:26:07 GMT

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