Re: [xml-dev] Unqualified forms and Inheritance by Restriction

["Pete Cordell" <petexmldev@codalogic.com>]

Does it help if you have <xs:restriction base="xs:string"/> for E2 in the 
second case?

Pete Cordell
Codalogic Ltd
Interface XML to C++ the easy way using C++ XML
data binding to convert XSD schemas to C++ classes.
Visit http://codalogic.com/lmx/ or http://www.xml2cpp.com
for more info
----- Original Message ----- 
From: "Toby Considine" <Toby.Considine@gmail.com>
To: "xml-Dev Listserv" <xml-dev@lists.xml.org>
Sent: Friday, March 16, 2012 1:47 PM
Subject: [xml-dev] Unqualified forms and Inheritance by Restriction


I have a family of schemas for energy markets that are derived from a root
abstract schema. In most cases, the derived types extend the abstract types
by adding additional elements. This inheritance by addition is
straight-forward.



For one key abstract type, I use inheritance by restriction. Derived types
must have all the elements of the root type, but they may be restricted to a
few enumerated values. Consider the following, simplified and stripped down:



Root Schema:

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema";
xmlns="VIPRE Anti-phishing found a known bad URL in your email message. It 
was deleted or quarantined, depending on your settings, and replaced with 
this message. The anti-phishing setting is located in File>Settings under 
the Email Protection tab."
targetNamespace="VIPRE Anti-phishing found a known bad URL in your email 
message. It was deleted or quarantined, depending on your settings, and 
replaced with this message. The anti-phishing setting is located in 
File>Settings under the Email Protection tab."
elementFormDefault="qualified">

<xs:element name="A" type="AType"/>

<xs:complexType name="AType" abstract="true">

                <xs:sequence>

                                <xs:element name="E1" type="xs:string"/>

                                <xs:element name="E2" type="xs:string" />

                </xs:sequence>

</xs:complexType>



Derivative schema

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema";
xmlns="VIPRE Anti-phishing found a known bad URL in your email message. It 
was deleted or quarantined, depending on your settings, and replaced with 
this message. The anti-phishing setting is located in File>Settings under 
the Email Protection tab."
xmlns:base="VIPRE Anti-phishing found a known bad URL in your email message. 
It was deleted or quarantined, depending on your settings, and replaced with 
this message. The anti-phishing setting is located in File>Settings under 
the Email Protection tab."
targetNamespace="VIPRE Anti-phishing found a known bad URL in your email 
message. It was deleted or quarantined, depending on your settings, and 
replaced with this message. The anti-phishing setting is located in 
File>Settings under the Email Protection tab."
elementFormDefault="qualified">

<xs:import namespace="VIPRE Anti-phishing found a known bad URL in your 
email message. It was deleted or quarantined, depending on your settings, 
and replaced with this message. The anti-phishing setting is located in 
File>Settings under the Email Protection tab."
schemaLocation="Base.xsd"/>

<xs:element name="ARestricted" type="ARestrictedType"/>

<xs:complexType name="ARestrictedType" abstract="false">

<xs:complexContent>

                <xs:restriction base="base:AType">

                                <xs:sequence>

                                                <xs:element name="E1"
type="xs:string" fixed="foo"/>

                                                <xs:element name="E2">


<xs:simpleType>


<xs:restriction base="xs:token">


<xs:enumeration value="fie"/>


<xs:enumeration value="foe"/>


</xs:restriction>


</xs:simpleType>

                                                </xs:element>

                                </xs:sequence>

                </xs:restriction>

</xs:complexContent>

</xs:complexType>



The derivative schema is invalid. In particular, when processed, each
element in ARestricted generates the following error:
"rcase-NameAndTypeOK.1: The declarations' {name}s and {target namespace}s
are not the same: restriction element is <xs:element name="itemDescription">
and base element is <xs:element name="itemDescription">."

http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/#rcase-NameAndTypeOK



I can avoid the error if I change each of the schemas from
elementFormDefault="qualified" to elementFormDefault="unqualified". The
derived schema now validates using XML Spy and Liquid XML Studio. When I use
the Liquid Technologies code generation tool to create software objects, the
objects generate XML that looks like what I want.



Here's the question:



Should I be looking for some side effect of switching these schemas from
qualified to unqualified? Is there some hidden problem I will come upon if I
require conforming schemas to be unqualified? I generally prefer "qualified"
for the esthetic reason that I like to see explicit type derivations
(prefices) in the schema. I do not have a feel for what else may be
affected.



Thanks



tc



  _____

"You can cut all the flowers but you cannot keep spring from coming."
-Pablo Neruda.

  _____


Toby Considine
TC9, Inc

TC Chair: oBIX & WS-Calendar

TC Editor: EMIX, EnergyInterop

U.S. National Inst. of Standards and Tech. Smart Grid Architecture Committee





Email:  <mailto:Toby.Considine@fac.unc.edu> Toby.Considine@gmail.com
Phone: (919)619-2104

http://www.tcnine.com/
blog: www.NewDaedalus.com