The FTP server had closed the connection due to idling. I expected isAvailable() would return false in that case, but it returned true. So, my program continued and called listFiles(). It threw an FTPConnectionClosedException or a broken PIPE socket exception.
Sending a NOOP before each command would be inefficient. If I see a famous FTP client like FileZilla, I can see that it immediately recognises server disconnection and displays the disconnection message (such as 421 Connection timed out). I understand that Apache Commons FTP is only for basic protocol, but since many users would want that feature (immediate recognition for server disconnection), I wish there was a code snippet for that. I am going to experiment it on my own by extending the FTPClient class. PS: I am sorry for the wrong tag in the subject. > Sent: Wednesday, May 11, 2016 at 11:32 PM > From: sebb <seb...@gmail.com> > To: "Commons Users List" <user@commons.apache.org> > Subject: [NET] was: [FTP] No disconnected event? Should poll periodically? > > I assume you are referring to Commons NET here. > > You should probably use isAvailable() instead as that performs more checks. > > However as the method Javadoc says, the only sure way to check if the > connection is still available is to use it. > > Commons NET does not provide idle connection checking and so there is > no event for it. > > You will need to implement your own checks, e.g. using sendNoOp() > every so often. > Care must be taken to ensure that you only send such probes when the > connnection is not being used otherwise you might interfere with other > commands. > > Note that Commons NET is only intended to provide basic access to > Internet protocols. > For example it is not intended to replace a full FTP Client, merely to > provide some building blocks. > > On 11 May 2016 at 15:09, Mailing User <mailingl...@mail.com> wrote: > > I think the connection to a FTP server can be lost. Reasons can be, network > > disconnection or client idling. > > > > If that happens, can I be notified of the disconnection? I cannot find any > > "event" for that. Should I keep polling the state by periodically calling > > "isConnected()"? > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: user-unsubscr...@commons.apache.org > > For additional commands, e-mail: user-h...@commons.apache.org > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: user-unsubscr...@commons.apache.org > For additional commands, e-mail: user-h...@commons.apache.org > > --------------------------------------------------------------------- To unsubscribe, e-mail: user-unsubscr...@commons.apache.org For additional commands, e-mail: user-h...@commons.apache.org
