Procedure calls are nothing new.
Procedure calls don't have to initiate with your actions on your computer, however. They can also be remotely and automatically triggered by an event or script on another computer. Remote procedure calls have been a part of corporate middleware and enterprise software products for decades, letting machines based on different platforms understand each other and automatically execute tasks. For example, a Macintosh on a corporate network might make a procedure call to a Microsoft Windows machine on the network. Several developers see great promise in extending the notion of remote procedure calls to XML-based information, which is where the XML RPC protocol comes in.