XMLRPC Tutorial on XMLRPC Data Model
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the xml-rpc specification defines six basic data types and two compound data types that represent combinations of types.

basic data types in xml-rpc

type value examples
int or i4 32-bit integers between - 2,147,483,648 and 2,147,483,647.

<int>27</int>

<i4>27</i4>
double 64-bit floating-point numbers

<double>27.31415</double>

<double>-1.1465</double>
boolean true (1) or false (0)

<boolean>1</boolean>

<boolean>0</boolean>
string ascii text, though many implementations support unicode

<string>hello</string>

<string>bonkers! @</string>
datetime.iso8601 dates in iso8601 format: ccyymmddthh:mm:ss

<datetime.iso8601>

20021125t02:20:04

</datetime.iso8601>

<datetime.iso8601>

20020104t17:27:30

</datetime.iso8601>
base64 binary information encoded as base 64, as defined in rfc 2045

<base64>sgvsbg8sifdvcmxkiq==</base64>

these basic types are always enclosed in value elements. strings (and only strings) may be enclosed in a value element but omit the string element. these basic types may be combined into two more complex types, arrays, and structs. arrays represent sequential information, while structs represent name-value pairs, much like hashtables, associative arrays, or properties.

arrays are indicated by the array element, which contains a data element holding the list of values. like other data types, the array element must be enclosed in a value element. for example, the following arraycontains four strings:

<value>
   <array>
      <data>
         <value><string>this </string></value>
         <value><string>is </string></value>
         <value><string>an </string></value>
         <value><string>array.</string></value>
      </data>
   </array>
</value>

the following array contains four integers:

<value>
   <array>
      <data>
         <value><int>7</int></value>
         <value><int>1247</int></value>
         <value><int>-91</int></value>
         <value><int>42</int></value>
      </data>
   </array>
</value>

arrays can also contain mixtures of different types, as shown here:

<value>
   <array>
      <data>
         <value><boolean>1</boolean></value>
         <value><string>chaotic collection, eh?</string></value>
         <value><int>-91</int></value>
         <value><double>42.14159265</double></value>
      </data>
   </array>
</value>

creating multidimensional arrays is simple - just add an array inside of an array:

<value>
   <array>
      <data>
		
         <value>
            <array>
               <data>
                  <value><int>10</int></value>
                  <value><int>20</int></value>
                  <value><int>30</int></value>
               </data>
            </array>
         </value>
			
         <value>
            <array>
               <data>
                  <value><int>15</int></value>
                  <value><int>25</int></value>
                  <value><int>35</int></value>
               </data>
            </array>
         </value>
			
      </data>
   </array>
</value>

a simple struct might look like:

<value>
   <struct>
      <member>
         <name>givenname</name>
         <value><string>joseph</string></value>
      </member>
		
      <member>
         <name>familyname</name>
         <value><string>dinardo</string></value>
      </member>
		
      <member>
         <name>age</name>
         <value><int>27</int></value>
      </member>
   </struct>
</value>

this way you can implement almost all data types supported by any programming language.

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