The controller sends a notification to the agent when the file updates are retrieved, and {HEAD ~ the agent} retrieves {TAIL ~ the file} updates from the controller 
retrieves
The controller sends a notification to the agent when the file updates are retrieved , and { HEAD ~ the agent } retrieves { TAIL ~ the file } updates from the controller
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH