You can use eXtensible Markup Language (XML) to format parameters in the message body of an Oracle ATG Web Commerce platform REST Web Services request.

Enclose all message body content in a parameters element as shown in the example below. Include each parameter in a separate child element. Use the name of the parameter as its element name. For positional parameters that do not have names, use the arg1, arg2, arg3 convention to name their elements. See Positional Parameters.

<parameters>
  <arg1>MyUsername</arg1>
  <arg2>MyPassword</arg2>
  <atg-rest-user-input>MyMessageId</atg-rest-user-input>
</parameters>

Make sure that you specify Content-Type: application/xml in the HTTP message. See Setting the Content-Type Value.