CS176A - HOMEWORK ASSIGNMENT 2
Due: May 1 (By 11:59pm)

Objectives

Assignment Details

The server will start in passive mode listening on a specified port for a transmission from a client. Separately, the client will be started and will contact the server on a given IP address and port number that must be entered via the command line.

The client should start with the string "Enter command:". It should accept a single keypress as input. The single key should be a "1", "2", or "3". The client should ensure that no other input is accepted. This digit should then be sent to the server. The server should take the following actions:

• For a "1", return the date and time in the unix date format. For example: "Sat Apr 1 08:00:00 PST 2006".

• For a "2", return a maximum of 100 lines of the command "ls -l" for the directory in which the server is run. Be sure to include only the lines including file names (e.g., not the "total" line). For example,

  -rwx------    1 almeroth faculty      1405 Mar 18 11:54 176.txt
  drwx------    2 almeroth faculty      4096 Apr  1 05:20 handouts
  -rwx------    1 almeroth faculty        93 Apr  1 05:15 notes
  -rwx------    1 almeroth faculty        22 Mar 27 19:17 run
  

• For a "3", return the string "Thank You." and then close.

See below for the output from a sample run.

Examples

Starting the Server

Assume that you started a server on machine 128.111.49.44, listening to port number 32000. The syntax should look like the following:
csil-machine1> server 32000
• In this example, “server” should be replaced by one of the names given below in the Assignment Turnin section.
• The server should not produce any output but should end after responding to a client string of "3".



Starting the Client

Assume that you started a client that wanted to communicate with a server on machine 128.111.49.44, listening to port number 32000. The syntax should look like the following:
csil-machine2> client 128.111.49.44 32000
• In this example, “client” should be replaced by one of the names given below in the Assignment Turnin section.



Client Input/Output Example

csil-machine2> client 128.111.49.44 32000
Enter command: a
Improper input.
Enter command: 1
Sat Apr 1 08:00:00 PST 2006
Enter command: 4
Improper input.
Enter command: 3
Thank You.
csil-machine2>



Language Choice and File Names

You will choose either Java or C for this assignment. In either case, you must turn in exactly four programs (all headers, etc. should be included in the one file). If you are using C, the programs should be:
• Client in C using UDP: client_c_udp.c
• Server in C using UDP: server_c_udp.c
• Client in C using TCP: client_c_tcp.c
• Server in C using TCP: server_c_tcp.c

To compile your C code, use the following four commands:


• "gcc -g -o client_c_udp client_c_udp.c"
• "gcc -g -o server_c_udp server_c_udp.c"
• "gcc -g -o client_c_tcp client_c_tcp.c"
• "gcc -g -o server_c_tcp server_c_tcp.c"

For Java, the program names should be:

• Client in Java using UDP: client_java_udp.java
• Server in Java using UDP: server_java_udp.java
• Client in Java using TCP: client_java_tcp.java
• Server in Java using TCP: server_java_tcp.java

To compile your Java code, use the following commands:


• "javac client_java_udp.java"
• "javac server_java_udp.java"
• "javac client_java_tcp.java"
• "javac server_java_tcp.java"

NOTE: Pay attention to all of these directions carefully. An automated checker will be used and if there are any deviations, you will lose points! (There is a CS176A-related point to this note as well: as you will learn, protocols are absolutely precise, there can be no deviation in syntax. Programming this assignment is straightforward, but those who earn a 100 (or more) will have followed the directions exactly.)

Grading Guidelines

You may use pieces of code from the Internet to help you do this assignment (e.g. basic socket code). However, this is just like citing a passage from a book, so if you copy code, you must cite it. To do this, put a comment at the beginning of your code that explains exactly what you have copied, who originally wrote it, and where it came from.

Below is a breakdown of points for this assignment. In addition to correctness, part of the points count towards how well code is written and documented. NOTE: good code/documentation does not imply that more is better. The goal is to be efficient, elegant and succinct!

• 20 pts: UDP client
• 20 pts: TCP client
• 20 pts: UDP server
• 20 pts: TCP server
• 20 pts: Documentation/Proper References

An assignment in C will be awarded up to 10 extra points.

Assignment Turnin

The assignment should be submitted using the course web site. Because the web site only allows one file to be submitted, you should use a commonly available tool (tar or zip) to combine your four files into a single file.

Cheating Policy

This assignment is to be done individually. Cheating will not be tolerated. Please read the UCSB Academic Code of Conduct to find out more about Student Conduct and Discipline. Of particular relevance to this assignment is the need to properly cite material you have used. Failure to do so constitutes plagiarism.