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Right, the labels/help/hint can't be determined from a general Schema, nor
can the prototype instance.
So when designing XForms we decided to start with a prototype instance that
sets the complex content by example, and use XPath to point from UI controls
and their labels/help/hint to the value node in the prototype; XML Schema is
used to declare the simple types for validating those nodes, and for
whole-document validation at the end just before submission in clients that
support Schema validation. (XForms also uses XPath expressions for a few
other things like validation constraints that must be true before
submission, the readonly bit, calculated values, etc.)
So, XForms is pretty much just XPath-based glue between a human-readable UI
layer and a data layer containing a prototype instance and a Schema
description and optional XPath for additional constraints. Control is done
through DOM Events expressed in XML (the recently PR'd XML Events), and
presentation through CSS.
Plus, it's designed to be incorporated into browsers, not just as a
standalone premium office product.
What's not to like ;-)
Leigh.
-----Original Message-----
From: Patrick.Garvey@talaris.com [mailto:Patrick.Garvey@talaris.com]
Sent: Friday, August 08, 2003 3:59 PM
To: xml-dev@lists.xml.org
Subject: RE: [xml-dev] Looking for a schema->html form XSL transform
Very good point about xsd:any and the general case.
Using this method requires that the designer know what can be in the schema,
and thus what can be on the form. And before anyone jumps all over me for
imposing my imperfect cognitive frames on the possible contents of a
document, I've changed my address 5 times in the last 10 years and the DMV
change of address form has looked the same every time :-)
Patrick
-----Original Message-----
From: Klotz, Leigh [mailto:Leigh.Klotz@pahv.xerox.com]
Sent: Friday, August 08, 2003 3:51 PM
To: Patrick Garvey (Engineering); Klotz, Leigh; 'cameron@shorter.net';
'xml-dev@lists.xml.org'
Subject: RE: [xml-dev] Looking for a schema->html form XSL transform
That's great reference for the original question. Thank you for showing how
XSLT can be used to generate an XForms document.
As for the non-generative question, the lack of a single top-level element
was just an example, and can of course be worked around by specifying,
outside the Schema, a toplevel element. But I believe that in the general
case, an XML Schema cannot be used to generate a unique prototype document
that can be edited just by filling in simple element content and attributes.
If the user agent is allowed to alter the structure of the document (i.e.,
by y adding elements and attributes where none were generated from the
transformation on the Schema), then that begs the question of whether the
document is indeed generated from the Schema, since the user is in this case
generating the document.
Here are two examples of Schemas that do not have enough information about
their structure to generate documents by any means other than infinite
enumeration of all legal documents followed by a "Y or N?" dialog, or by
using an editor that already understands Schema structures and letting the
user add any structure necessary.
1. xsd:any
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema";
elementFormDefault="qualified"
targetNamespace="http://www.example.com";
xmlns:e="http://www.example.com";>
<xs:element name="instance">
<xs:complexType>
<xs:sequence>
<xsd:any namespace="##any" processContents="skip" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
You might argue that this is a trival Schema, but in fact I extracted it
from the Schema for XForms itself.
2. The Schema for modularized XHTML 1.1:
http://www.w3.org/TR/xhtml-m12n-schema/xhtml-m12n-schema.html#a_schema_xhtml
11
Note that if you can write an XSLT transformation that takes this as input
and produces an editor that can output all documents that are valid by this
Schema, you will have produced a general XHTML editor!
Leigh.
-----Original Message-----
From: Patrick.Garvey@talaris.com [mailto:Patrick.Garvey@talaris.com]
Sent: Friday, August 08, 2003 2:00 PM
To: Leigh.Klotz@pahv.xerox.com; cameron@shorter.net; xml-dev@lists.xml.org
Subject: RE: [xml-dev] Looking for a schema->html form XSL transform
How is an XML Schema non-generative?
There are top level elements that show what the root element is. This
element has a type, which has child elements, etc.
If there are multiple top level elements in the schema, just pass in a
parameter to the stylesheet with the name of the root element you want in
your result document and follow the tree all the way to the end.
See http://www.xml.com/pub/a/2003/01/15/transforming-schemas.html?page=1,
or the "User Interface Generation" chapter from the following paper, which
describes how one can generate an XForms from a schema using XSLT (and
borrowed heavily from the examples in the xml.com article):
http://dream.sims.berkeley.edu/CDE/report/go-five-final-report.html
-------------------------------------
Patrick Garvey
Document Engineer
Talaris Corporation
1400 Fashion Island Boulevard
San Mateo, CA, 94404
(650) 212 8434 phone
(650) 212 8499 fax
pgarvey@talaris.com
http://www.talaris.com
Red Herring "Top 10 Companies to Watch"
InfoWorld "Top 100 Technology Innovators"
Enterprise 2002 "Top 5 New Big Thing"
-----Original Message-----
From: Klotz, Leigh [mailto:Leigh.Klotz@pahv.xerox.com]
Sent: Friday, August 08, 2003 1:22 PM
To: 'Cameron Shorter'; 'xml-dev@lists.xml.org'
Subject: RE: [xml-dev] Looking for a schema->html form XSL transform
An XML Schema is not generative; i.e., doesn't have enough information in it
to provide the basic structure of a document, so you need to start with
something that says what the root element it, what elements come next, etc.
If you start with a sample XML document with blanks for the content, then
you can use any XForms processor to do what you're asking. You do need to
provide the human-readable labels for the fields you want the user to edit,
and an XPath expression that says where those fields are in the initial
document. If you specify one or more XML Schemas, they will be used to
validate the resulting document before it is POSTed back as XML.
See http://www.w3.org/MarkUp/Forms and
http://www.w3.org/MarkUp/Forms/Test/ImplementationReport.html two
fully-conformant implementations, one of which runs inside Internet
Explorer. There are also some JavaScript-based implementations; they aren't
fully conformant with the XForms spec, but might be good enough for your
purposes. IBM has one available form download and testing.
Leigh.
-----Original Message-----
From: Cameron Shorter [mailto:cameron@shorter.net]
Sent: Friday, August 08, 2003 2:01 PM
To: xml-dev@lists.xml.org
Subject: [xml-dev] Looking for a schema->html form XSL transform
Hi,
I want to:
1. Use XSL to build a HTML form from a schema, then
2. Build XML from the elements in the form and POST the xml back to a
server.
Does anyone know of XSL or javascript I can use which will address either of
the above?
--
Cameron Shorter http://cameron.shorter.net
Open Source Developer http://generguide.sourceforge.net
http://mapbuilder.sourceforge.net
http://geotools.org
Senior Software Engineer http://www.adi-limited.com
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