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RE: Reusing the XMLSchema simpleType element in an own schema

From: <gino.marckx@belgacom.be>
Date: Wed, 28 Aug 2002 13:00:38 +0200
Message-ID: <06187E0800A0D21192DD0008C75DE4DC0861CCF0@acar41.bc>
To: jeni@jenitennison.com
Cc: xmlschema-dev@w3c.org

Hi Jeni,

I tried your suggestion this morning already and it did not do what I wanted.  In the "http://www.w3.org/2000/10/XMLSchema", simpleType seems to be defined multiple times and I do not seem to be able to get the version I want.  If I follow your suggestion, the schema forces me use the following structure in the data document:

	<xsd:simpleType name="xxx">
		<xsd:simpleDerivation></xsd:simpleDerivation>
	</xsd:simpleType>

That is why I tried to solve it by mimicing how elements are defined in XMLSchema.

But thanks anyway,
Gino.

-----Original Message-----
From: Jeni Tennison [mailto:jeni@jenitennison.com]
Sent: 28 August 2002 12:52
To: gino.marckx@belgacom.be
Cc: xmlschema-dev@w3c.org
Subject: Re: Reusing the XMLSchema simpleType element in an own schema


Hi Gino,

> I want to reuse the simpleType element definition we all use for
> defining our own schema's, in a schema. In other words, I want to be
> able in the XML document, using my schema, to define simpleType
> elements as data.
>
> Example:
> <types xmlns:xsd="http://www.w3.org/2000/10/XMLSchema">
>         <type name="myStringType" type="xsd:string"/>
>         <type name="myEnumerationBasedOnStringType">
>                 <xsd:simpleType>
>                         <!-- If the following is impossible, it could restrict xsd:string too -->
>                         <xsd:restriction base="myStringType">
>                                 <xsd:enumeration>Possible value</xsd:enumeration>
>                         </xsd:restriction>
>                 </xsd:simpleType>
>         </type>
> </types>

OK, so you want to say that the type element can contain a
xsd:simpleType element, as defined in the W3C XML Schema namespace.

> I tried to specify the type element like the following, but on
> validation I always get the same error stating that the type cannot
> be found, even when I import the schema:
>
> <xsd:element name="type">
>         <xsd:complexType>
>                 <xsd:sequence>
>                         <xsd:element name="simpleType" type="xsd:anySimpleType" minOccurs="0"/>
>                 </xsd:sequence>
>                 <xsd:attribute name="name" value="xsd:string"/>
>                 <xsd:attribute name="type" value="xsd:QName" use="optional"/>
>         </xsd:complexType>
> </xsd:element>

Here, you're saying that the type element can hold a simpleType
element (in your namespace or in no namespace, depending on the value
of elementFormDefault on your xsd:schema element). I think, from the
example that you've given, that you want it to hold a *xsd:simpleType*
element. To do that, you need to refer to the xsd:simpleType element
from the content model, as follows:

<xsd:element name="type">
  <xsd:complexType>
    <xsd:sequence>
      <xsd:element ref="xsd:simpleType" minOccurs="0"/>
    </xsd:sequence>
    <xsd:attribute name="name" value="xsd:string"/>
    <xsd:attribute name="type" value="xsd:QName" use="optional"/>
  </xsd:complexType>
</xsd:element>

To refer explicitly to an element in another namespace, you *must*
have an xsd:import element that references that namespace (although it
doesn't necessarily have to point to a schema). So you need:

<xsd:import namespace="http://www.w3.org/2001/XMLSchema" />

or something similar at the top of your schema.

Cheers,

Jeni

---
Jeni Tennison
http://www.jenitennison.com/

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Received on Wednesday, 28 August 2002 07:00:43 GMT

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