XML Remote Procedure Calls

XML is a data encoding technique that can be used to represent data and data requests that are transmitted between components on a single node or across a network. It does not defi ne what data should be transferred (that is the responsibility of the application developer, and any data including ASN.1-encoded SNMP data can be encapsulated in XML), nor does it defi ne how the XML documents should be exchanged.

XML documents may be transferred using any data or fi le transfer process. Various processes have been applied, from UDP or TCP, through the File Transfer Protocol (FTP) and the Hypertext Transfer Protocol (HTTP). The early uses of XML utilized a remote procedure call (RPC) mechanism based on HTTP-this made good sense because XML is closely related to HTML, which HTTP is designed to carry, and because HTTP contains basic get and put operations.

XML-RPC is still in use and has been successful, but it is considered by some to have too much overhead. A more object-oriented approach was desired, and so the Simple Object Access Protocol (SOAP) was devised.