Distributed Computer Systems (RMI)

You are required to implement a very simple FTP server and client with NETBEANS software.

The server (applies to both TCP sockets and RMI) can take the list of available files as command-line arguments or through the use of appropriate graphical user interface.

For example:

java [url removed, login to view] [url removed, login to view] [url removed, login to view] [url removed, login to view]

or:

java [url removed, login to view] [url removed, login to view] [url removed, login to view] [url removed, login to view]

The client should take the server address and port as command-line arguments.

For example:

java [url removed, login to view] 192.168.1.1 5115

or:

java [url removed, login to view] [url removed, login to view] 5115

Then, the client should wait for user input from STDIN, and should support the following three commands:

 dir -- retrieves the list of files offered, and prints them on the screen

 get <filename> -- retrieves the file with the given filename

 send <filename> -- sends the file with the given filename

 bye -- closes the communication with the server and exits

Any other input should be ignored (not exiting!) with a simple “syntax error” message printed on the screen. (i.e. adequate and meaningful error messages provided in the event of errors)

Socket interface:

For the TCP sockets implementation, your client should connect to the server, and send it a String (use ObjectInputStream and ObjectOutputStream) containing one of the following commands, and expecting the respective responses from the server:

 dir -- The server sends back a String[] containing the filenames of available files

 blocks filename (for instance: blocks [url removed, login to view]) -- The server sends back an integer (use [url removed, login to view]()) denoting the number of 1024-byte blocks in that file. For instance, if a file has 5000 bytes, it has 5 blocks (4 blocks of 1024 bytes and a final block of 904 bytes)

 get filename block (for instance: get [url removed, login to view] 4) -- The server sends back a 1024 byte long block of the file. The last block of the file may have less than 1024 bytes.

RMI interface:

For the RMI implementation, your server should support the following simple API:

* String[] dir() -- returns an array of String containing the filenames of all available files

* int blocks(String filename) -- returns the number of blocks that the given file has

* byte[] getBlock(filename, blockNumber) -- returns a 1024-byte-long block of the file. The last block of the file may have less than 1024 bytes.

Java Socket IO

Project ID: #5393843

About the project