RE: [wsia] Proposal for simple properties mechanism based on XFor ms

A small addendum to my proposal of yesterday. Re-reading the XForms spec, 
it seems that the <instance> can have multiple elements inside 
it, so that we can remove the redundant <values> tag everywhere. Thus, the 
example will look a lot cleaner:

 

1. 
Description of an entity with two properties - TitleText (string) and ShowHelp 
(boolean):

<xf:model>

  
<xf:instance>

       <TitleText 
/>

       <ShowHelp 
/>

  
</xf:instance>

  
<xf:bind nodeset="ShowHelp" type="xsd:boolean" />

  <!-- default type is ##any 
-->

</xf:model>

 

2. Querying 
of the value of TitleText:

<xf:model>

  
<xf:instance>

       <TitleText 
/>

  
</xf:instance>

</xf:model>

 

3. Response 
to the query:

<xf:model>

  
<xf:instance>

       <TitleText>This is the title 
of the text</TitleText>

  
</xf:instance>

</xf:model>

 

Gil

P.S. Anybody with insider information into XForms? The Working Draft is 
very confusing and I'm still not sure whether multiple elements are 
possible.

  
-----Original Message-----
From: Gil Tayar 
  [mailto:]
Sent: Sun, August 25, 2002 
  15:30
To: ; 
  
Subject: [wsia] Proposal for simple 
  properties mechanism based on XForms

  
Objectives:

  
1. 
  Separate Property definition (meta-data) from property values from 
  property querying.

  
2. Do it simply.

  
 

  
General 
  model (as defined by XForms 1.0 in http://www.w3.org/TR/xforms/)

  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  
<xf:model>

  
  
  <xf:instance>

  

  
    <values>

  
        
  <p1>value1</p1>

  
        
  <p2>value2</p2>

  
        ...

  
    
  </values>

  
  </xf:instance>

  

  
  <xf:bind nodeset="p1" type="xsd:string" /> <!-- 
  defines that 'p1' is of type string --> 
  
  <xf:bind nodeset="..." type="...:foobar" /> <!-- 
  defines that 'p1' is of type foobar, which is defined in the 
  <schema> below -->

  
  <xsd:schema>

  
    ...

  
    <xsd:simpleType 
  id="foobar">...</xsd:simpleType>

  
  </xsd:schema>

  
</model> 

  
 

  
This 
  defines property values (<xf:instance>) and meta-data (<xf:bind>) 
  with supporting type definitions.

  
 

  
To 
  specify only meta-data, specify only empty placeholders for instance data 
  (e.g. without values), and optionally specify bind tags (and supporting type 
  definitions) for defining types. This is 
  conformant to the view of XForms, where the only place to define validation 
  constraints is in the <bind> tag, which specifies for nodes in the 
  <instance> what their schema is.

  
To 
  specify only values, do not specify bind tags.

  
To 
  specify querying of values, specify only empty placeholders for instance data 
  (e.g. without values). This means that to 
  retrieve all values of the instance data, just pass back what was received in 
  the meta-data description.

  
 

  
Constraints for 
  simplicity:

  
~~~~~~~~~~~~~~~~~~~~~

  
1. All 
  instances are of the form:

  
  
  <values>

  
   
  <property-name>property-value</property-name>

  
   ...

  
  </values>

  
  This means that the root tag contains only child tags with no 
  attributes. The sub-values of these tags are 
  unconstrained.

  
  
  The child tag is a property whose name 
  is the property's name and it's content is the property's 
  value.

  
 

  
2. 
  The types for the property values must be one of the pre-defined types defined 
  in XML Schema. The default if not defined in a 
  <bind> is "##any".

  
3. The 
  bind tag must reference (using 
  its "nodeset" attribute) only propeties, i.e. the child tags (e.g. 
  p1...).

  
 

  
Example:

  
~~~~~~~

  
1. 
  Description of an entity with two properties - TitleText (string) and ShowHelp 
  (boolean):

  

  
<xf:model>

  
  
  <xf:instance>

  

  
    <values>

  
       <TitleText 
  />

  
       <ShowHelp 
  />

  
    </values>

  
  
  </xf:instance>

  
  
  <xf:bind nodeset="ShowHelp" type="xsd:boolean" />

  
  <!-- default type is ##any 
  -->

  
</xf:model>

  
 

  
2. 
  Querying of the value of TitleText:

  

  

  
<xf:model>

  
  
  <xf:instance>

  

  
    <values>

  
       <TitleText 
  />

  
    </values>

  
  
  </xf:instance>

  
</xf:model>

  
 

  

  
3. 
  Response to the query:

  
<xf:model>

  

  
  
  <xf:instance>

  

  
    <values>

  
       <TitleText>This is the title 
  of the text</TitleText>

  
    </values>

  
  
  </xf:instance>

  
</xf:model>

  
 

  
Extensions allowed by implementors

  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  
1. 
  Implement full "bind" functionality (e.g. define "required", "constraints", 
  "min"... on each part of instance data). Clients not aware of these can ignore 
  them.

  
2. The 
  types for the property values can be any defined in the XML Schema. Clients 
  not aware of these can ignore them and assume "xsd:##any".

  
3. Remove 
  constraints on the bind tag.

  
4. Remove 
  constraint on structure of the values.

  
 

  
Comments, anybody?

  
Gil Tayar

  
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