Re: [ubl] Validating UBL 2.0 genericode files with Altova XMLSpy

["Anthony B. Coates (Miley Watts)" <abcoates@mileywatts.com>]

On Thu, 28 Sep 2006 03:47:59 +0100, <juerg.tschumperlin@minedu.govt.nz>  
wrote:

> Am I right to conclude that the XML Catalog specification should be more  
> specific, and define which of the two uri MUST be used: the namespace  
> uri, or the schemaLocation URI. With that ambiguity, different tool  
> vendors will implement it differently, causing this very issue.

This is beyond the control of the XML Catalog specification, because it is  
specified in the W3C XML Schema specification.  To summarise, a  
schemaLocation can be included in an XML instance file, but it is only  
considered to be a hint to the Schema validator.  The Schema validator can  
choose to ignore it (and often will for security reasons).

Also, the Schema spec more-or-less suggests that if there is no  
schemaLocation, it is worth trying to use the namespace URI as a Schema  
location.  Of course, this won't work if you have more than one Schema for  
your namespace (as sometimes happens).

The XML Catalog specification can only help in terms of how to map URIs,  
and it does have special support for XML files with a DTD "DOCTYPE"  
declaration, because they are so well know.  With XML Schema, there are  
too many possibilities, there was no way the XML Catalog spec could try to  
control or limit this.  It's up to the software vendors themselves (e.g.  
Altova) to make the best possible use of XML Catalogs.

Cheers, Tony.
-- 
Anthony B. Coates
Senior Partner
Miley Watts LLP
Experts In Data
+44 (79) 0543 9026
Data standards participant: ISO 20022 (ISO 15022 XML), ISO 19312,  
UN/CEFACT TMG, MDDL, FpML, UBL.