CIS 432/532 Introduction to Computer Networks
Fall 2001

Program #1 FAQ

1. Q: Which languages can I write this assignment in?
   A: C or C++. And it must compile on the department's Solaris machines.
   
   
2. Q: I haven't programmed in C or C++ much. What books should I use to learn about these languages?
   A: For C, the definitive reference is:
   
   The C Programming Language, Second Edition by Brian W. Kernighan and Dennis M. Ritchie. Prentice Hall, Inc., 1988. ISBN 0-13-110362-8 (paperback), 0-13-110370-9 (hardback). Web site for this book is at: http://cm.bell-labs.com/cm/cs/cbook/ and you can order it at Amazon.com among other places.
   
   For C++, I highly recommend:
   
   Practical C++ Programming By Steve Oualline, 1st Edition. O'Reilly, September 1995. ISBN 1-56592-139-9. You can also find this at Amazon.com.
   
   
3. Q: What changes have you made to the protocol spec based on feedback from student questions?
   A: (1) When the server relays a message to a group of users, it should use "message nick message", where nick is the nickname of the person sending the message and message is the text being sent. (2) Likewise, a private message being relayed by the server has the form "private nick message". (3) The user message should return the IP address and port number. (4) The users and list messages should end with a blank line. (5) The server should respond with an error when the user tries to login more than once.
   
   
4. Q: Any typos in the assignment?
   A: I changed a typo in the example so that hamburgler types "leave mcdonalds" when leaving the group.
   
   
5. Q: In your example, why does Joe get notified of his nickname change when your protocol says that clients aren't notified of a nickname change?
   A: This is a little tricky. In the *protocol* the client does not receive any message back from the server except for "success". But in the *user interface* the client parses the success message and prints out "Joe changes his name to hamburgler".
   
   
6. Q: With the list command, should users who are not in a group be listed?
   A: No.
   
   
7. Q: How does the user log in? Is there a "/user" command?
   A: There is no "/user" command. The client does the login procedure automatically for the user, before printing a prompt and accepting any commands.
   
   
8. Q: How does the client know the user's login name?
   A: The client can use the getenv() command to find the value of the USER environment variable, which is set to the user's login name. You can find out more about this command by typing 'man getenv()'.
   
   
9. Q: When a user logs in, the default nick is set to the user's login name. What if someone else is already using that nickname?
   A: When you try to set the default nickname, and someone else is already using that nick, append a sequence number to the new default nickname to make it unique. You can use any algorithm you want to pick the sequence number; this does not need to be standardized.
   
   
10. Q: When I run your solution client, I get some really strange results. The parameters for the program are different from the spec.
    A: You are using a different chat program that resides on the Solaris systems. Be sure to type "./chat" to run the program that is in the current directory, or put "." at the beginning of your path.