Setting the KeepAlive property to a value of true specifies
that a background worker thread will be created to monitor the
command channel for an FTP connection and periodically send NOOP
commands to the server if no commands have been sent recently. This
can prevent the server from terminating the client connection during
idle periods where no commands are being issued. However, it is
important to keep in mind that many servers can be configured to also
limit the total amount of time a client can be connected to the
server, as well as the amount of time permitted between file
transfers. If the server does not respond to the NOOP command, this
option will be automatically disabled for the remainder of the client
session.
It is recommended that you only enable this option if the
connection to the FTP server must be maintained for a relatively long
period of time where there will be periods of inactivity. Never make
the assumption that this option can prevent the server from
terminating the connection. Most sites, particularly public FTP
servers accessed over the Internet, have fairly restrictive policies
designed to prevent clients from maintaining long-term connections.
In most cases, if there are periods of time where your application
will not be transferring files, it is more appropriate to disconnect
from the server and then reconnect at a later point rather than
attempting to hold the connection open.
The default value for this property is false. This property is
only meaningful for FTP connections.