This assignment is intended to reinforce the principles of the inter-process communication and the end-to-end argument. It will also make you familiar with Java and its networking API. You have to develop a simplified version of a ftp program (similar to the one described in the end-to-end argument paper) using the stream sockets available in java.net package.

The program will consist of a client and a server. The client will need to register itself with the server for the first time using simple credentials (exact details of these credentials are left to you to decide). These credentials will be used by the server to authenticate the client for any further sessions. After the client is authenticated, the server will accept a request from the client for transferring a file. If the requested file exists then it will be sent across to the client. The contents of the file will be encrypted, using some simple technique, such as the security API provided by Java, before the transmission. If the requested file does not exist then the server will indicate an error message and close the socket connection. Your program should also support a mode in which the client can specify multiple files, as a single transaction, to be transferred. The semantics of the transfer mechanism in such a case is same as that for the single file transfer.

A check should be performed to ensure that the file transfer was successfully completed (i.e., the contents of the original file and its copy on the server are identical). If the transfer was not successful then the transferring task should automatically be retried. After a certain number of retries (a parameter that can be adjusted), a failure message should be displayed if the transfer is still unsuccessful and the socket connection should close.

Your design should consider the principles of the end-to-end argument. You must explicitly indi- cate, in the report, the design decisions that you have taken, in order to achieve the above mentioned functionality, that have been influenced by the end-to-end argument. Also, the consequences of these decisions should be discussed.

Although, the assignment mentions about one client and one server, if you design the server such that it can accept multiple concurrent requests, using the threads of Java, then you will get an extra credit. Your program should handle appropriate exceptions. The program must run on any two machines (server on one machine and client(s) on the other) from the following list:

sl253-rrpc01.cs.iupui.edu - 10.234.140.27
sl253-rrpc02.cs.iupui.edu - 10.234.140.28
sl253-rrpc03.cs.iupui.edu - 10.234.140.29
sl253-rrpc04.cs.iupui.edu - 10.234.140.30
sl253-rrpc05.cs.iupui.edu - 10.234.140.31
sl253-rrpc06.cs.iupui.edu - 10.234.140.32

Please note that your Pegasus/Tesla accounts will work on these set of machines. Please employ good software engineering principles in your design and implementation. Provide adequate documen- tation of your programs. Create a makefile for your program. Submit all the source files (including the readme, sample outputs and make files) by using submitd command on Pegasus/Tesla. Also, hand-in a hard-copy of the report at the beginning of the class on the due date.