Re: v98b PartyId needs min length of 1

[Doug Bunting <dougb62@yahoo.com>]

Scott,

I agree and would like to see us go further.  One of the common
problems with XML syntax is the meaning of required and optional with
respect to empty elements and attributes.  The problem is the #PCDATA
(for elements in a DTD), CDATA (for attributes in a DTD) and string
(for elements and attributes in an XML Schema) datatypes do not require
any content.  So, an empty element satisfies a schema that requires
that element.

This is a major security and interoperability issue that schemas and
DTD's alone do not address.  For example, applications are often
written without a full understanding of this problem.  They are liable
to fail in weird and mysterious ways when attempting to access and use
empty strings from an XML document.

I would recommend defining a subtype of string in our schema with the
restriction you've outlined below.  We should use that new datatype
rather than "string" throughout our schema.  (Note: We're lucky here
because the problem doesn't have as elegant a solution when using a DTD
for validation.)

To my knowledge, we have defined no meaning for an empty string
anywhere in the ebXML TR&P headers.  As such, this restriction should
not effect the text of our document.

thanx,
   doug

--- Scott Hinkelman <srh@us.ibm.com> wrote:
> Looks like we need to change the schema for PartyId and add
> constraint for
> min length of 1, as in:
> 
>      <xsd:element name = "PartyId">
>           <xsd:complexType>
>                <xsd:simpleContent>
>                     <xsd:restriction base = "xsd:string">
>                          <xsd:minLength value = "1"/>
>                          <xsd:attribute name = "type" type =
> "xsd:string"/>
>                     </xsd:restriction>
>                </xsd:simpleContent>
>           </xsd:complexType>
>      </xsd:element>
> 
> Thanks,
> Scott Hinkelman, Senior Software Engineer
> XML Industry Enablement
> IBM e-business Standards Strategy
> 512-823-8097 (TL 793-8097) (Cell: 512-940-0519)
> srh@us.ibm.com, Fax: 512-838-1074
> 
> 
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