Historical data about the XML Protocol activity
  - End of 1999, early 2000: growing interest in the use of XML in
    distributed applications communication.
- Proliferation of different
    XML-based protocols.
- September 2000: creation of the XML Protocol Working Group to
    address the need for an XML-based communication protocol, chartered to
    design four components:
    
      - an envelope encapsulating XML data.
- a convention for RPC (Remote Procedure Call) applications.
- a data serialization mechanism.
- a mechanism to use HTTP as a transport mechanism.