how to enforce atleast one occurence for 2 element types in XSD schema

Question

Hi,

I need to develop an xsd for the scenario. where i have 2 element of types Server1 and Server2. There can be any number of occurances for Server1 and Server2 but atleast one of the occurance is mandatory either Server1 or Server2.

<element name="Server1">
  <complexType>
   <sequence>
    <element name="hostName" type="string"/>
    <element name="portNumber" type="integer"/>
    <element name="userName" type="string"/>
   </sequence>
  </complexType>
</element>
<element name="Server2">
  <complexType>
   <sequence>
    <element name="hostName" type="string"/>
    <element name="portNumber" type="integer"/>
   </sequence>
  </complexType>
</element>

Thanks Ravi

Answer 1

You can wrap them to choice schema element with maxOccurs attribute set to unbounded.

Sample:

<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified">
    <element name="root">
        <complexType>
            <choice maxOccurs="unbounded">
                <element name="Server1">
                    <complexType>
                        <sequence>
                            <element name="hostName" type="string"/>
                            <element name="portNumber" type="integer"/>
                            <element name="userName" type="string"/>
                        </sequence>
                    </complexType>
                </element>
                <element name="Server2">
                    <complexType>
                        <sequence>
                            <element name="hostName" type="string"/>
                            <element name="portNumber" type="integer"/>
                        </sequence>
                    </complexType>
                </element>
            </choice>
        </complexType>
    </element>
</schema>

Answer 2

I'm not sure it's the best possibility by any means, but one possibility would be for Server1 and Server2 to be just type names, and then create an element that's a union of Server1 and Server2.

<xsd:comlexType name=Server1>
   <sequence>
   // ...
   </sequence>
</xsd:complextype>

<xsd:complexType name=Server2>
// ...
</xsd:complexType>

<element name="Server">
   <xsd:union memberTypes = "Server1 Server2" />
</element>