 specific variable. The agent based on design could respond to this message with a GET-RESPONSE message indicating that a change request was successful or an error message indicating the reason for change request failure. In the example below, the SET request is to change the status of link-1 for card-6 in shelf-2 to "Offline." It can be seen that the SET message body will have information about what needs to be set and where the information needs to be set. SET message with XML: <setenvp setenvp to= 'host' xmlns= 'setinfo:client' xmlns: setenvp= URI <setenvp Header> Fundamentals of EMS, NMS and OSS/BSS <setenvp: setenvp from= 'host' id=`stream-id' xmlns='setinfo:client' xmlns:setenvp=`-URI </setenvp:Header> <setenvp:Body> <iq type= 'set' to='mib@host' id='query-id'> <query xmlns=`setinfo:iq: 'shelf-2.card-6.link-1. status'/> <var>Offline</var> /query> </iq> </setenvp:Body> </setenvp:setenvp> 4. TRAP message: This message allows the agent to spontaneously inform the manager of an important event. Traps are very effective in sending fault information. The body of the trap message sent by the agent will contain an identifier and the information details on the reason for the generated trap. These XML traps can be collected by the manager and parsed for details that can be used for debugging the error scenario captured by the TRAP message. TRAP message with XML: <trapenvp trapenvp to= 'host' xmlns='trapinfo:client xmlns:trapenvp=`--URI- - --'> <trapenvp:Header <trapenvp:trapenvp 1 from=`host id=`stream-id' xmlns='trapinfo:client' xmlns:trapenvp=`- </trapenvp:Header> <trapenvp:Body> <iq type='trap' to= 'mgr@host' id=`query-id'> <query xmlns='trap:iq:Trunk.ABC.FaultDetected'> <trapenvp:Fault> <faultcode>Fault Code here</faultcode> <faultstring>Fault String here</faultstring> </trapenvp:Fault> </query> </iq> </getenvp:Body> </ getenvp:getenvp > 18.5.2 Transfer of Message The XMLP envelope needs to be packaged with the UDP header with details of source and destination port. Figure 18.2 shows the XMLP envelope with the UD