AIA Query operations - how to return no elements?

Question

Hello,
I've noticed all query response messages for different EBOs found in AIA metadata are defined following the below pattern (ItemEBO as an example):
Simple query response:
<xsd:complexType name="QueryItemResponseEBMType">
     <xsd:complexContent>
          <xsd:extension base="corecom:EBMType">
               <xsd:sequence>
                    <xsd:element name="DataArea" type="QueryItemResponseDataAreaType"/> <---- one and only one
               </xsd:sequence>
          </xsd:extension>
     </xsd:complexContent>
</xsd:complexType>
List query response:
<xsd:complexType name="QueryItemListResponseEBMType">
     <xsd:complexContent>
          <xsd:extension base="corecom:EBMType">
               <xsd:sequence>
                    <xsd:element name="DataArea" type="QueryItemListResponseDataAreaType" maxOccurs="unbounded"/> <---- one or more
               </xsd:sequence>
          </xsd:extension>
     </xsd:complexContent>
</xsd:complexType>
As shown above the schema force responses to always contain at least one DataArea.
But what if a queried resource returns no results ? What should be returned in a response? It looks to me a business fault is the only solution here but it doesn't seem to be the right solution for most cases.
Thanks,
Piotr
Edited by: Piotr Bazan on Jul 18, 2012 6:44 AM

Answer 1

Hey Rahul,
thanks for your input.
Returning an empty DataArea creates a need for an extra check on the client site (not a big deal maybe). Wouldn't it be more natural to return no DataArea (not allowed by the current schema) at all or throw a business exception (not all cases are business exceptions)?
Is there a purpose for restricting its occurence to 'at least 1'?
Thanks,
Piotr