i didn't know too much about it,
but you can find more info from here
Apache FtpServer
FtpServer is a server component for Avalon Phoenix that allows remote FTP client to attach and download files. The client software can be any type of FTP client written in any language. The criteria for eligibility is RFC compliance.
The server uses several components. Some of the components have multiple implementations. For example user management has implementations that will use LDAP, JDBC and Cornerstone's Store facility for storage.
http://incubator.apache.org/projects/ftpserver/
find out more!
Regards
Jitender