ActionScript for Flash MX: The Definitive Guide, 2nd Edition By Colin Moock
Chapter 18. ActionScript Language Reference
XMLSocket.close( ) Method
Flash 5
terminate an open connection to a server application
socket.close()
Description
The close( ) method severs the communication link between socket and a server application. Once close( ) has been executed on socket, subsequent attempts to invoke send( ) on socket fail. Likewise, the server application will no longer be able to send data to Flash through socket.
Note that close( ) has no effect if the socket is already closed or was never connected. Furthermore, close( ) does not trigger the onClose( ) handler of the socket object onClose( ) is triggered only by a server-side connection closure.