What is the role of XML in managing open source apps?

XML is widely used in many administrative applications. It is an ideal language for configuration information and is convenient for transmitting information to and from applications, because XML documents may be parsed by software applications, and are also human-readable, making them much easier to debug than binary-formatted integration payloads. The latest wave of integration mechanisms -- Web Services -- uses XML not only as the payload formatting language, but also as the interface definition and configuration. My firm has used open source SOAP applications and had great success with them; they run for months with no support intervention required. Any programmer or administrator worth his or her salt should get familiar with XML.