Top Most What is XML-RPC

XML-RPC is a protocol that uses XML messages to perform 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 sufficiently, XML-RPC = HTTP + XML + 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 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 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. 
The official XML-RPC specification is available at XML-RPC.com. Dozens of XML-RPC implementations are available in Perl, Python, Java, and Ruby. See the XML-RPC home page for a complete list of implementations.