How would you describe this in XML/XSD?

I am not sure what would be a good XML structure for the following...

Assume that a field type, say <person>, can have different "flavors", e.g. either the person is a local reference defined 开发者_开发技巧only by some ID, or it is a global reference with various address elements associated. What would be a good XML structure for this so that it becomes easy to describe in a schema (an xsd file)?

I see two strategies - bot both with some major drawbacks:

Either the person type is defied as a separate element, say <type>, but then I guess a schema cannot tell which of the type specific fields that are mandatory:

<person>
   <type>local</type>
   <id>12345</id>
</person>
<person>
   <type>global</type>
   <name>Some Name</name>
   <address>Some Street 42</address>
   <city>Some City</some>
</person>

In this case <id> should only be mandatory for "local" person types, and similarly with the fields for "global" person types.

The other strategy is to define a new node type for each person sub-type, but then we cannot tell that each sub-type is in fact just a flavor of <person>:

<personLocal>
   <id>12345</id>
</personLocal>
<personGlobal>
   <name>Some Name</name>
   <address>Some Street 42</address>
   <city>Some City</some>
</personGlobal>

What is a good strategy for modeling structures like this?

You can use the following (partial) schema:

    <xs:element name="person">
      <xs:complexType>
        <xs:choice>
          <xs:element name="id" type ="xs:int"/>
          <xs:sequence>
            <xs:element name="name" type="xs:string" />
            <xs:element name="address" type="xs:string" />
            <xs:element name="city" type="xs:string" />
          </xs:sequence>
        </xs:choice>
      </xs:complexType>
    </xs:element>

Important: The xs:choice tag.

This will result in the following:

• When the first tag inside the person tag is the id tag, no other tags are allowed.
• When the first tag inside the person tag is the name tag, the address and city tags are mandatory, the id tag is not allowed.

For me, I do that like this :

<parent>
  <local>
    <person>
      <name />
      <adress />
      <city />
    </person>    
  </local>
  <global>
    <person>
      <name />
      <adress />
      <city />
    </person>    
  </global>
<parent>

Or like this :

<person type='local'>
  <name />
  <adress />
  <city />
</person>    
<person type='global'>
  <name />
  <adress />
  <city />
</person>

:)

One workarround (the one that I probably ends up with) is to define the schema as below, because different person types (there are more than the two examples I explained) may contain some of the same fields:

<xs:element name="person">
<xs:complexType>
  <xs:choice>
    <xs:element name="local">
      <xs:complexType>
        <xs:sequence>
          <xs:element name="id" type ="xs:int"/>
        </xs:sequence>
      </xs:complexType>
    </xs:element>
    <xs:element name="global">
      <xs:complexType>
        <xs:sequence>
          <xs:element name="name" type="xs:string" />
          <xs:element name="address" type="xs:string" />
          <xs:element name="city" type="xs:string" />
        </xs:sequence>
      </xs:complexType>
    </xs:element>
  </xs:choice>
</xs:complexType>