W3C home > Mailing lists > Public > xmlschema-dev@w3.org > December 2001

RE: SOAP and WSDL and inheritance by restriction

From: James Pasley <james.pasley@capeclear.com>
Date: Wed, 12 Dec 2001 18:06:33 -0000
To: "'Eddie Robertsson'" <eddie@allette.com.au>
Cc: <xmlschema-dev@w3.org>
Message-ID: <003801c18337$bc22ed10$9400a8c0@REXX>

Eddie,

Thanks for the info, the base Array definitions refers to an attributeGroup
which includes the arrayType attributes, so I think the restriction is
correct in this respect. Sorry, if leaving this definition out of the
original mail caused confusion.

However, you will notice the wsdl:arrayType attribute on the definition
of this attribute. The WSDL spec describes it as follows:

	At the time of this writing, the XSD specification does not have a
	mechanism for specifying the default value of an attribute which
	contains a QName value.  To overcome this limitation, WSDL
	introduces the arrayType attribute (from namespace
	http://schemas.xmlsoap.org/wsdl/) which has the semantic of
	providing the default value.  If XSD is revised to support this
	functionality, the revised mechanism SHOULD be used in favor of the
	arrayType attribute defined by WSDL.

Was such a mechanism ever added to the schema specification?

James.

-----Original Message-----
From: Eddie Robertsson [mailto:eddie@allette.com.au]
Sent: Tuesday, December 11, 2001 10:29 PM
To: James Pasley
Cc: xmlschema-dev@w3.org
Subject: Re: SOAP and WSDL and inheritance by restriction


> Typically, when you define arrays you inherit from this definition and
> restrict the xs:any's in it to the particular of type in your array, so
from
> my reading of the inheritance rules, an array of floats should look as
> follows:
>
> <xs:complexType name="ArrayOfFloat">
>   <xs:complexContent>
>     <xs:restriction base="soapenc:Array">
>       <xs:sequence>
>         <xs:element name="item" minOccurs="0" maxOccurs="unbounded"
> type="xs:float" />
>       </xs:sequence>
>       <attribute ref="soapenc:arrayType" wsdl:arrayType="xs:float[]"/>
>     </xs:restriction>
>   </xs:complexContent>
> </xs:complexType>

This is not valid. It seems as though you're trying to add a new attribute
(soapenc:arrayType) to the derived type and you can never add anything when
you
derive a new type by restriction, only restrict the content of the base
type. If
you need to add an attribute you need to first derive the specialized type
by
restriction and then add the attribute in a new type derived by extension
from
this type.

> However, the WSDL specification ( http://www.w3.org/TR/wsdl ) contains the
> following example of an array of floats:
>
> <complexType name="ArrayOfFloat">
>   <complexContent>
>     <restriction base="soapenc:Array">
>       <attribute ref="soapenc:arrayType" wsdl:arrayType="xsd:float[]"/>
>     </restriction>
>   </complexContent>
> </complexType>
>
> Now the Schema Primer states the following:
>
>     Notice that types derived by restriction must repeat all
>     the components of the base type definition that are to be
>     included in the derived type
>
> So (and here's the question), is the example from the WSDL specification
> incorrect as it neither repeats the xs:any or replaces it with a more
> restrictive element. Am I right in thinking that it actually defines an
> complex type which can not contain child elements at all?

Your correct in that the above type wouldn't contain any child elements but
it's
also invalid for the same reason I gave above.

Cheers,
/Eddie
Received on Wednesday, 12 December 2001 13:04:48 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 11 January 2011 00:14:25 GMT