ConversationSetup Caller Responder Start ConversationRequested Caller SendMessage xml-document RequestConversation.xsd ConversationAccepted Responder SendMessage xml-document AcceptConversation.xsd ConversationOver Responder SendMessage xml-document Refuse.xsd MetaConversation-2.1.xml Caller A Responder B CPDone ChildReturn Done ConversationOver Caller SendMessage xml-document ClosingConversation.xsd ConversationOver