Re: [regrep] [XML Schema issue] Replace choice with type substitution

[Farrukh Najmi <farrukh.najmi@sun.com>]

Attached is the changes to rim.xsd if we went ahead with the proposed 
change. The lines starting with '-' are being removed. The line starting 
with '+' are being added. Other lines are shown for visual context.

Notice how much cleaner the schema gets.

Farrukh Najmi wrote:

>
> Team,
>
> In new V3 schema we have consistently used type substitution instead 
> of choice construct when defining XMl schema. Choice in the pinion of 
> many is not very object oriented and implementation experience has 
> shown that it complicates design.
>
> I would like to ask if any one has objections if we replace 
> occurrences of <choice> in the schema with type substitution. Here is 
> an example of how teh proposal effects the schema:
>
> Old Way
> --------
> In query.xsd the definition of AdhocQueryRequest looks like:
>
> <sequence>
>   <element ref = "tns:ResponseOption" minOccurs="1" maxOccurs="1" />
>   <choice minOccurs="1" maxOccurs="1">
>     <element ref = "tns:FilterQuery"/>
>     <element ref = "tns:SQLQuery"/>
>   </choice>
> </sequence>
>
> New Way
> -------
> Above Old Way would look like this under the proposal:
>
> <sequence>
>   <element ref = "tns:ResponseOption" minOccurs="1" maxOccurs="1" />
>   <element name="Query" type="tns:AdhocQueryType" minOccurs="1" 
> </sequence>
>
> Where AdhocQueryType is the base type for both SQLQueryType and 
> FilterQueryType.
>
> Benefits
> ---------
> Now code can be written using Object oriented principals so that there 
> is a AdhocQueryType class that is extended by SQLQueryType and 
> FilterQueryType classes. Either type of query may be abstractly 
> represented as a AdhocQueryType.
>
> Thanks for your input on this issue.
>
>
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-- 
Regards,
Farrukh


Index: rim.xsd
===================================================================
RCS file: /cvsroot/ebxmlrr/ebxmlrr-spec/misc/schema/v3/rim.xsd,v
retrieving revision 1.18
@@ -708,43 +708,11 @@
 	<element name = "ObjectRefList" type="tns:ObjectRefListType"/>
 
 
-	<complexType name = "LeafRegistryObjectListType">
-		<choice minOccurs = "0" maxOccurs = "unbounded">
-			<element ref = "tns:ObjectRef"/>
-			<element ref = "tns:Association"/>
-			<element ref = "tns:AuditableEvent"/>
-			<element ref = "tns:Classification"/>
-			<element ref = "tns:ClassificationNode"/>
-			<element ref = "tns:ClassificationScheme"/>
-			<element ref = "tns:ExternalIdentifier"/>
-			<element ref = "tns:ExternalLink"/>
-			<element ref = "tns:ExtrinsicObject"/>
-			<element ref = "tns:Organization"/>
-			<element ref = "tns:RegistryPackage"/>
-			<element ref = "tns:Service"/>
-			<element ref = "tns:ServiceBinding"/>
-			<element ref = "tns:SpecificationLink"/>
-			<element ref = "tns:User"/>
-			<element ref = "tns:Registry"/>
-			<element ref = "tns:Federation"/>
-			<element ref = "tns:Subscription"/>
-      
-		</choice>
+	<complexType name = "RegistryObjectListType">  
+    <sequence>
+      <element name="RegistryObject" type="tns:RegistryObjectType" minOccurs="1" maxOccurs="1"/>
+    </sequence>
 	</complexType>
-	<element name = "LeafRegistryObjectList" type = "tns:LeafRegistryObjectListType"/>
-	
-	<complexType name = "RegistryObjectListType">
-		<complexContent>
-			<extension base = "tns:LeafRegistryObjectListType">
-				
-					<choice minOccurs = "0" maxOccurs = "unbounded">
-						<element ref = "tns:RegistryEntry" />
-						<element ref = "tns:RegistryObject"/>
-					</choice>
-			</extension>
-		</complexContent>
-	</complexType>
-	<element name = "RegistryObjectList" type = "tns:RegistryObjectListType"/>
-	
+	<element name = "RegistryObjectList" type = "tns:RegistryObjectListType"/>  	
 	
 </schema>