As developers in today’s world, we should be familiar with XML. On the surface, it is a group of data that is packaged and organized neatly into opening and closing tags. A deeper look tells us that this structure of XML makes it easy for machines to read and process. Thus, while XML can be hard on human eyes, we know it is designed for machine communication. However, without any sort of agreed structure of the XML document by the machines, the advantages of XML are effectively eliminated. This is where XML-RPC comes in.
RPC is an acronym for Remote Procedure Call; developed by David Winer of UserLand software in 1996. Its purpose is to allow applications, regardless of how different each program or the purpose of each program, to communicate with each other across a network in a standardized manner.
In computer terms, a procedure call is that which gets executed when the operating system communicates to the input devices about what you are doing: Which key did you just hit on the...