It was first created by Userland Software in 1995, and later picked up by Microsoft. However Microsoft considered it too simple, and started adding functionality. After several rounds of this the standard was no longer so simple, and has re-emerged as SOAP.
See also: SOAP, CORBA, DCOM, web service
XML-RPC (http://www.xml-rpc.com/)
wikipedia.org dumped 2003-03-17 with terodump