What is XML-RPC ?

XML-RPC is a protocol that uses XML messages to perform RPC (Remote Procedure Calls)

Requests are encoded in XML and sent via HTTP POST; XML responses are embedded in the body of the HTTP response.

More succinctly, XML-RPC = HTTP + XML + RPC (Remote Procedure Calls)

Because XML-RPC is platform independent, diverse applications can communicate with one another. For example, a Java client can speak XML-RPC to a Perl server.

To get a quick sense of XML-RPC, here is a sample XML-RPC request to a weather service (with the HTTP Headers omitted) :

<?xml version="1.0" encoding="ISO-8859-1"?>

<methodCall>

   <methodName>weather.getWeather</methodName>

   <params>

      <param><value>10016</value></param>

   </params>

</methodCall>

The request consists of a simple <methodCall> element, which specifies the method name (getWeather) and any method parameters (zip code).

Here is a sample XML-RPC response from the weather service :

<?xml version = "1.0" encoding="ISO-8859-1"?>

<methodResponse>

   <params>

      <param>

          <value><int>65</int></value>

      </param>

   </params>

</methodResponse>

The response consists of a single <methodReponse> element, which specifies the return value (the current temperature). In this case, the return value is specified as an integer.

In many ways, XML-RPC is much simpler than SOAP, and therefore represents the easiest way to get started with Web services.