The SendResponse method is used to respond to a
command issued by the client from within an OnCommand event
handler. Command responses are normally handled
by the server as a normal part of processing a command and this
method is only used if the application has implemented custom
commands or wishes to modify the standard responses sent by the
server. The message may be a maximum of 2048 characters and may
include embedded carriage-return and linefeed characters. If no
message is specified, then a default message will be sent based on the
result code.
Result codes must be three digits (in the range of 100 through 999)
and although this method will support the use of non-standard result
codes, it is recommended that the client application use the standard
codes defined in RFC 959 whenever possible. The use of non-standard
result codes may cause problems with FTP clients that expect specific
result codes in response to a particular command.
This method should only be called once in response to a command
sent by the client. If a result code has already been sent in response
to a command and this method is called, it will fail and return a
value of zero. This is necessary because sending multiple result codes
in response to a single command may cause unpredictable behavior by
the client.