Computer System Assignment 1
The Trivial File Transfer Protocol (TFTP) is an Internet software utility for transferring files that is simpler to use than the File Transfer Protocol (FTP) but less capable. It is used where user authentication and directory visibility are not required. For example, it is used by Cisco routers and switches to transfer images of the operating system from/to the devices.
NOTE: TFTP’s port is 69 (a system/OS port). This is below 1024 and therefore you cannot bind a Socket to it unless you have administrative access rights on the machine you are working. To avoid any complications you can use any port > 1024 to bind server sockets.
Task 1: Implementation of the Trivial File Transfer Protocol (TFTP)
For this task you need to implement (in Java) the Trivial File Transfer Protocol (TFTP) as specified in RFC 1350 (Links to an external site.). You will submit source code for a client and server application that ‘speak’ the TFTP protocol. You will built your protocol on top of UDP. Compared to the specifications in the RFC, you will implement a slightly simplified version:
• Support for octet mode only. The files should be transferred as a raw sequence of bytes. Do not read, write or transfer files as characters.
• Support only for error handling when the server is unable to satisfy the request because the file cannot be found.
• No support for error handling when data duplication occurs.
The client and server applications should be simple Java console applications. The server should operate (i.e. read and write files) in the directory where it is started from. The server should support simultaneous file transfers to and from multiple clients. The client should just read command line arguments (or have a very simple console-based menu – e.g. “press 1 to store file, press 2 to retrieve file”) and execute user commands (i.e. reading or writing a file).
Hint: the simplest way to implement timeouts is by calling the setSoTimeout() method on the DatagramSocket objects (assuming that you are using blocking I/O). If the timeout expires, a java.net.SocketTimeoutException is raised, though the DatagramSocket is still valid.
Task 2: Implementation of an even simpler version of TFTP on top of TCP
For this task you will use TCP sockets to implement a protocol that operates like TFTP (i.e. supports only read and write operations). Given that TCP supports in-order, reliable data transport, you should not implement the relevant mechanisms described in RFC 1350 (ACKs, retransmissions). The client and server applications should be equally simple, as in Task 1. The server must be able to handle multiple file transfers.
Task 3: Interoperability with existing implementations (5% bonus)
Given that the UDP version of TFTP client and server that you will implement must adhere to the respective RFC, both the client and server should be able to interoperate with other TFTP servers and clients, respectively, regardless of the programming language they are written. For this optional task, you are asked to demonstrate this interoperability by running your client with an existing third-party server, and your server with an existing third-party client.
Marking Criteria
You should make sure that your code compiles. Code which does not compile will receive at most 20%.
I will assess your assignment using the following criteria:
TFTP-UDP-Server (35%):
• Is the server-side of the protocol fully and correctly implemented (based on the specifications in the RFC)? i.e. read/write requests, acknowledgments, timeouts, error handling, support for simultaneous file transfers.
TFTP-UDP-Client (30%):
• Is the client-side of the protocol fully and correctly implemented (based on the specifications in the RFC)? i.e. read/write requests, acknowledgments, timeouts, error handling.
TFTP-TCP-Server (10%):
• Is the server-side of the protocol fully and correctly implemented? i.e. read/write requests, error handling, support for simultaneous file transfers.
TFTP-TCP-Client (10%):
• Is the client-side of the protocol fully and correctly implemented? i.e. read/write requests, error handling.
Description of Protocols (10%):
• Is there description for both protocols and how/where the specifications are implemented?
• Is the description well-written with clear references to the source code?
Other Characteristics (5%):
• Is the code commented appropriately?
• Is it indented correctly?
• Is naming of variables and methods sensible?
Interoperability (extra 5%):
• Is your implementation compatible with third-party TFTP servers and clients and have you demonstrated that it is?
Note that the maximum mark you can get is 100% and the extra 5% will be added to the mark to reach up to 100%.
Submission Guidelines
You should submit the coursework by the deadline posted on Sussex Direct (and the submission link on Canvas). Standard penalties for late submissions will apply. You will need to submit a .zip file containing the following:
• Well-formatted and well-documented source code (written in Java) in 4 separate Netbeans projects that can be compiled and run. The Netbeans projects, named TFTP-UDP-Server, TFTP-UDP-Client, TFTP-TCP-Server and TFTP-TCP-Client, respectively, will include all required source code to execute the 2 different file transfer protocols.
• A short report (up to 2000 words) describing your protocols, the source code and the design decisions that you made.
• Screenshots and details about third-party TFTP clients and servers you used to demonstrate interoperability of your implementation (optionally for the extra 5%).
Please do not put your names on your submissions, but do include your candidate number. Failure to submit source code, as described in the first bullet, will result to a zero mark as I will not be able to assess your programming effort.
Plagiarism and Collusion
• The coursework you submit is supposed to have been produced by you and you alone. This means that you should not: work together with anyone else on this assignment
• give code for the assignment to other students
• request help from external sources
• do anything that means that the work you submit for assessment is not wholly your own work, but consists in part or whole of other people’s work, presented as your own, for which you should in fairness get no credit
If you need help ask your tutor The University considers it misconduct to give or receive help other than from your tutors, or to copy work from uncredited sources, and if any suspicion arises that this has happened, formal action will be taken. Remember that in cases of collusion (students helping each other on assignments) the student giving help is regarded by the University as just as guilty as the person receiving help, and is liable to potentially receive the same penalty. Also bear in mind that suspicious similarities in student code are surprisingly easy to spot and sadly the procedures for dealing with it are stressful and unpleasant. Academic misconduct also upsets other students, who do complain to us about unfairness. So please don’t collude or plagiarise.