XSD/JAXB question

Question

I'm just starting out on using XSD/JAXB, and I was wondering how best to approach this:
<likes>
  <like val="color">red</like>
  <like val="number">7</like>
</likes>That is, the value of the val attribute determines the type of content that the like element should accept. For example:
<xs:simpleType name="colors">
  <xs:restriction base="xs:string">
    <xs:enumeration value="red"/>
    <xs:enumeration value="orange"/>
    <xs:enumeration value="yellow"/>
    <xs:enumeration value="green"/>
  </xs:restriction>
</xs:simpleType>
<xs:simpleType name="numbers">
  <xs:restriction base="xs:int">
    <xs:minInclusive value="3"/>
    <xs:maxExclusive value="20"/>
  </xs:restriction>
</xs:simpleType>But how to use the attribute value to determine the acceptable element content? I have managed to use union to define element content that is a union of acceptable input types, but since this is not restricted by the attribute, you could end up with invalid XML like:
<likes>
  <!-- invalid xml when content is a union of types -->
  <like val="color">7</like>
  <like val="number">red</like>
</likes>Any takers?
Thanks, Neil

Answer 1

<xs:element name="likes">
<xs:complexType>
<xs:sequence>
<xs:sequence>
<xs:element name="like" type="colors"/>
</xs:sequence>
<xs:sequence>
<xs:element name="like" type="numbers"/>
</xs:sequence>
</xs:sequence>
</xs:complexType>
</xs:element>
thanks,
Deepak