A W3C XML Schema Language schema for XML-RPC

<?xml version="1.0"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">

  <!-- The only two possible root elements are methodResponse and
       methodCall so these are the only two I use a top-level
       declaration for. --> 

  <xsd:element name="methodCall">
    <xsd:complexType>
      <xsd:all>
        <xsd:element name="methodName">
          <xsd:simpleType>
            <xsd:restriction base="ASCIIString">
              <xsd:pattern value="([A-Za-z0-9]|/|\.|:|_)*" />
            </xsd:restriction>
          </xsd:simpleType>
        </xsd:element>
        <xsd:element name="params" minOccurs="0" maxOccurs="1">
          <xsd:complexType>
            <xsd:sequence>
              <xsd:element name="param"  type="ParamType" 
                           minOccurs="0" maxOccurs="unbounded"/>
            </xsd:sequence>
          </xsd:complexType>
         </xsd:element>
      </xsd:all>
    </xsd:complexType>  
  </xsd:element>

  <xsd:element name="methodResponse">
    <xsd:complexType>
      <xsd:choice>
        <xsd:element name="params">
          <xsd:complexType>
            <xsd:sequence>
              <xsd:element name="param" type="ParamType"/>
            </xsd:sequence>
          </xsd:complexType>
        </xsd:element>
        <xsd:element name="fault">
          <!-- What can appear inside a fault is very restricted -->
          <xsd:complexType>
            <xsd:sequence>
              <xsd:element name="value">
                <xsd:complexType>
                  <xsd:sequence>
                    <xsd:element name="struct"> 
                      <xsd:complexType> 
                        <xsd:sequence> 
                          <xsd:element name="member" 
                                       type="MemberType">
                          </xsd:element>
                          <xsd:element name="member" 
                                       type="MemberType">
                          </xsd:element>
                        </xsd:sequence>
                      </xsd:complexType>
                    </xsd:element>
                  </xsd:sequence>
                </xsd:complexType>
              </xsd:element>
            </xsd:sequence>
          </xsd:complexType>
         </xsd:element>
      </xsd:choice>
    </xsd:complexType>  
  </xsd:element>

  <xsd:complexType name="ParamType">
    <xsd:sequence>
      <xsd:element name="value" type="ValueType"/>
    </xsd:sequence>
  </xsd:complexType>

  <xsd:complexType name="ValueType" mixed="true">
    <!-- I need to figure out how to say that this
         is either a simple xsd:string type or that 
         it contains one of these elements; but that otherwise
         it does not have mixed content -->
    <xsd:choice>
      <xsd:element name="i4"            type="xsd:int"/>
      <xsd:element name="int"           type="xsd:int"/>
      <xsd:element name="string"        type="ASCIIString"/>
      <xsd:element name="double"        type="xsd:decimal"/>
      <xsd:element name="Base64"        type="xsd:base64Binary"/>
      <xsd:element name="boolean"       type="NumericBoolean"/>
      <xsd:element name="dateTime.iso8601" type="xsd:dateTime"/>
      <xsd:element name="array"         type="ArrayType"/>
      <xsd:element name="struct"        type="StructType"/>
    </xsd:choice>
  </xsd:complexType>

  <xsd:complexType name="StructType">
    <xsd:sequence>
      <xsd:element name="member" type="MemberType" 
                   maxOccurs="unbounded"/>
    </xsd:sequence>
  </xsd:complexType>

  <xsd:complexType name="MemberType">
    <xsd:sequence>
      <xsd:element name="name"  type="xsd:string" />
      <xsd:element name="value" type="ValueType"/>
    </xsd:sequence>
  </xsd:complexType>

  <xsd:complexType name="ArrayType">
    <xsd:sequence>
      <xsd:element name="data">
        <xsd:complexType>
          <xsd:sequence>
            <xsd:element name="value"  type="ValueType" 
                         minOccurs="0" maxOccurs="unbounded"/>
          </xsd:sequence>
        </xsd:complexType>
      </xsd:element>
    </xsd:sequence>
  </xsd:complexType>

  <xsd:simpleType name="ASCIIString">
    <xsd:restriction base="xsd:string">
      <xsd:pattern value="([ -~]|\n|\r|\t)*" />
    </xsd:restriction>
  </xsd:simpleType>

  <xsd:simpleType name="NumericBoolean">
    <xsd:restriction base="xsd:boolean">
      <xsd:pattern value="0|1" />
    </xsd:restriction>
  </xsd:simpleType>

</xsd:schema>