RE: Xforms 1.0 data model

Chris,
 
Thank you for your input.
 
We've looked at the requirement to have user-defined (i.e. "custom")
datatypes and are still grappling with the issue.  There are two fundamental
questions:
 
1) Should we have user-defined datatypes?
Pro:  They make the datamodel easier to use and more expressive
Con: They ratchet up the complexity of building an XForms client and may
alienate implementers targeting smaller devices
 
2) Once a user has defined a new type, how should it be referenced, as an
element name or via an attribute name?  Your example uses an element name.
Pro: Element names are more concise and generally regarded as "simpler"
Con: Using an element name means the grammar cannot be described by an XML
Schema without performing a transformation first.
 
These are not easy trade-offs to make, but I expect you'll probably see some
decisions in the next working draft (no I can't say when that will be).
 
Regards,
Rob
 

-----Original Message-----
From: Chris Judge [mailto:chris@formfill.com]
Sent: July 6, 2000 5:06 PM
To: www-forms@w3.org
Cc: mdubinko@cardiff.com; ssilvester@cardiff.com; schnitz@overflow.de;
dsr@w3.org
Subject: Xforms 1.0 data model



Hi all: 


In reviewing the XForms 1.0 Data Model (working draft 06 April 2000), I
noticed that several of the issues concern methods for reducing redundancy.
For example, section 4.4 (Monetary Values), states: 


[Issue: Do we want to support a means to indirectly specify facets when
there are many money values in a form, all of which accept the same
currency?]



A simple solution would be to define a new element in the <model> section
which defines custom data types. For example: 


... 

<model> 

<custom name="USDollars" type="money" currency="USD" min="0" digits="2"/> 

<custom name="phonenumber" type="string" mask="ddd?ddd-dddd"/> 

<group name="customer"> 

<string name="name"/> 

... 

<phonenumber name="voice"/> 

<phonenumber name="fax"/> 

<USDollars name="balancedue"/> 

<USDollars name="taxrate" digits="4"/> 

.... 

</group> 

</model> 


In the above example, "voice" and "fax" are both string data elements and
"balancedue" and "taxrate" are both money elements. Note also that "taxrate"
overrides the "digits" value defined in USDollars. 


The example should make it clear that a <custom> element can be used to
define a template for any of the pre-defined data elements. 


Finally, it would be easy to include scoping rules so that a <custom>
element defined within a <group> will only be available within that <group>.



Thanks for your time and if I'm mailing these suggestions to the wrong
people, please let me know. 




Chris Judge,

FormFill, Inc.

(512) 419-0304