How it Works

XML-RPC is described fully in Dave Winer's official specification. If you're curious, go ahead and take a look—it's a quick and straight-forward read.

On the wire, XML-RPC values are encoded as XML:

    <methodCall>
      <methodName>sample.sumAndDifference</methodName>
      <params>
        <param><value><int>5</int></value></param>
        <param><value><int>3</int></value></param>
      </params>
    </methodCall>

This is verbose, but compresses readily. It's also faster than you might expect—according to measurements by Rick Blair, a round-trip XML-RPC call takes 3 milliseconds using Hannes WallnЖfer's Java implementation.