Basics - reading/writing remote files using Java

Question

I started with requirement of reading and writing files in from/in a directory on a remote Ubuntu machine.

First, I wrote a Java program that could read,write files

Answer 1

If you want to access a filesystem on a remote computer, then this computer has to make his filesystem available with a service. Such a service is typically a background job, which handles incoming requests and returns a response, e.g. for authentication, authorization, reading and writing. The specification of the request/response pattern is called a protocol. Well known protocols are SMB (or SAMBA) on Windows or NFS on UNIX/LINUX. To access such a remote service you mount the remote filesystem on the level of the operating system and make it available locally as a drive on Windows or as mount point on UNIX.

Then you can access the remote file system from your Java program like any local file system.

Of course it is also possible to write your own file service provider (with your own protocol layer) and run it on the remote machine. As transport layer for such an endeavor sockets (TCP/IP) can be used. Another good transport layer would be the http protocol, e.g. with a restful service or something based on WebDav.