[DFDL-WG] XML Schema do type references have to be qualified?

[Steve Hanson]

Mike

You said "They all have the default unprefixed namespace as XML Schema's 
namespace." Technically your schema doesn't, it is using a different 
namespace.

        xmlns="http://www.ogf.org/dfdl/dfdl-1.0/XMLSchemaSubset"

I assume this is the standard 2001 XMLSchema namespace but cut-down so as 
to include just the constructs DFDL uses in its subset? 
Your namespace is not formally defined in the DFDL spec, and no such xsd 
is freely available at that URL, so your schema is not portable and fails 
to validate.
It also means that you can't strip out all the DFDL stuff and leave a pure 
XML Schema that any schema processor can handle.
Should we make your schema generally available at that URL, so it is 
resolved by schema processor? 

The IBM implementation does not define such a subset, it just uses the 
standard  2001 XMLSchema namespace "http://www.w3.org/2001/XMLSchema", and 
then does extra checking to flag constructs and types that are not in the 
DFDL subset. More work, but with all DFDL stuff removed the result is a 
pure XML Schema.

If I change your schema below to use the standard  2001 XMLSchema 
namespace then the IBM schema validator gives the following error...

        CTDX1100E : XSD: Type reference 
'http://www.w3.org/2001/XMLSchema#bar' is unresolved

...because it is looking in the 2001 XMLSchema namespace xsd for "bar". 

Regards

Steve Hanson
Architect, Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848



From:   Suman Kalia <kalia at ca.ibm.com>
To:     Mike Beckerle <mbeckerle.dfdl at gmail.com>
Cc:     dfdl-wg at ogf.org, dfdl-wg-bounces at ogf.org
Date:   19/03/2012 03:25
Subject:        Re: [DFDL-WG] XML Schema do type references have to be 
qualified?
Sent by:        dfdl-wg-bounces at ogf.org




Mike -  In the absence of explicit qualification, you cannot unambiguously 
say whether type bar is in your namespace or notarget namespace.  It 
should be flagged as an error in my opinion... 



From:        Mike Beckerle <mbeckerle.dfdl at gmail.com> 
To:        dfdl-wg at ogf.org 
Date:        03/16/2012 05:04 PM 
Subject:        Re: [DFDL-WG] XML Schema do type references have to be 
qualified? 
Sent by:        dfdl-wg-bounces at ogf.org 



So, I did some research, and answered my own question.

Section 3.3.4.2 of "Definitive XML Schema" by Walmsley, says that the
schema below is illegal as the name
"bar" will be interpreted as a reference to xsd:bar, not the 
targetNamespace.

However, it seems many XML Schema processors may be tolerant of this 
error.


On Fri, Mar 16, 2012 at 4:48 PM, Mike Beckerle <mbeckerle.dfdl at gmail.com> 
wrote:
> Suman,
>
> In and XMLSchema/DFDLSchema do I have to qualify the names of types?
>
> We have a bunch of test schemas written roughly like the example
> below. They all have the default unprefixed namespace as XML Schema's
> namespace. They also all have a target namespace.
>
> But some or all of the type references to named types use unqualified
> names. In my mind, that means they would be assumed to be in the XML
> Schema namespace, not the targetNamespace.
>
> On the other hand, the XML Schema validator doesn't complain. But that
> just means the schema is valid, not necessarily meaningful.
>
> Example here:
>
> <schema xmlns="http://www.ogf.org/dfdl/dfdl-1.0/XMLSchemaSubset"
> targetNamespace="http://example.com">
> <element name="foo" type="bar"/><!-- IS THIS LEGAL, no prefix on name> 
of the type. -->
> <complexType name="bar">
>   <sequence/>
> </complexType>
> </schema>
>
>
> Mike Beckerle | OGF DFDL WG Co-Chair
> Tel:  781-330-0412



-- 
Mike Beckerle | OGF DFDL WG Co-Chair
Tel:  781-330-0412
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