Data Communications

CS 43
Spring 1996


Thomas P. Kelliher
Hoyt 160
Office phone: 946-7290
Home phone: 946-3544 (emergencies only, please)
email: Send mail to kelliher AT DOMAIN
Office hours: MW 3:00--4:00pm. TR 1:00--2:30pm. Other times by appointment.


Hoyt 152
TR 7:00--8:30pm


The objectives of this class are:
  • To develop an awareness of the issues involved in distributed systems.
  • To achieve an understanding of the design models and principles associated with distributed systems.
  • To gain hands-on experience with distributed systems by configuring and studying client services on Unix workstations and through writing some distributed tools and applications.

This class will be run as a seminar/lab, with extensive discussions of the course material and several closed lab sessions. I assume that you are proficient in C and comfortable with Unix.

  1. A. S. Tanenbaum, Distributed Operating Systems, Prentice Hall, 1995.
You also need a Unix user's guide.

Suggested Materials:

A few 3.5" floppy diskettes. Preferably, these should be high density diskettes. You can use these to back-up your work. Ultimately, you are responsible for your files; within Unix, once a file has been removed, it's pretty much impossible to un-remove it.

Additional Resources:
These are, with the caveats noted, on reserve in Mack Library.
  1. W. R. Stevens, TCP/IP Illustrated, Vol. 1, Addison Wesley, 1994.
  2. W. R. Stevens, Advanced Programming in the Unix Environment, Addison Wesley, 1992.
  3. W. R. Stevens, Unix Network Programming, Prentice Hall, 1990. (This book has been ordered. I don't know when it will arrive.)
  4. P. W. Abrahams and B. R. Larson, Unix for the Impatient, 2nd edition, Addison Wesley, 1996.
  5. B. W. Kernighan, The C Programming Language, 2nd ed., Prentice Hall, 1988.
  6. D. Comer, Internetworking with TCP/IP, multiple vols., Prentice Hall, 1991--1992.


Grade Distribution

A = [90--100]
B = [80--90)

I use +/- grading sparingly.

Student Evaluation

There will be approximately 1000 total points for the class. They will be distributed as follows:

  1. Assignments --- Assignments will vary from programming writing and lab work (both in teams) to written assignments involving conceptual design. These assignments will be worth 70% of your final grade.

  2. Midterm --- There will be one in-class midterm on April 30. If you cannot take the midterm, please let me know as soon as possible. If you have a good reason, a make-up will be scheduled. This make-up must be scheduled to be taken within 48 hours of the in-class midterm. The midterm will be worth 20% of your final grade.

  3. Paper Presentation --- A set of research papers will be made available, with each student to pick a paper, write a one-page summary, and present it to the class. The summary will be due in class on May 8. The 20 minute presentations will be delivered on May 10 and the final period. You must use Powerpoint or WWW technology in delivering your presentation. This presentation will be worth 10% of your final grade.

No extra credit is available.

Course Handouts:

Most course handouts will be made available once in class. After that, they may be obtained from my personal home page on the World Wide Web (see the URL above). I also expect to distribute homework and exam solutions through my home page.


Attendance of classes is expected, but not required. Attendance is one of the factors examined in determining a borderline grade. It is your responsibility to catch up on missed class work.


Academic dishonesty will not be tolerated. Refer to the Handbook for Students and the Cheating Policy of the Department of Mathematics and Computer Science. Relevant points include:
  1. Program/module plagiarism will be suspected if a programming assignment results in two or more non-trivial program/module solutions so similar that one can be converted to another by a mechanical transformation.

  2. Cheating will be suspected if a student who was to complete an assignment cannot adequately explain the intricacy of their solution nor the techniques used to generate that solution.

A first offense will result in a grade of zero points for the assignment, Any subsequent offenses may result in a charge of academic dishonesty being filed with the Dean of the College, along with a grade of zero.

That said, I realize that Computer Science is best learned in a collaborative environment. You should work together and enhance each others' understanding of the material. However, you are ultimately responsible for your own learning. By depending too strongly on someone else for help with an assignment, you most definitely jeopardize your ability to perform well on a midterm or final. The name of anyone with whom you collaborate on an assignment must be listed on the assignment.

Unix and the Unix Lab:

Your programming assignments will be done using the GNU C++ ( g++) compiler under BSD/OS, an off-shoot of 4.4BSD Unix. Other Unix programming tools that you will be using include emacs (text editing) and gdb (source-level code debugger). There will be an intensive introduction to Unix during the second week of class. Programming tools will be introduced as the need arises.

The Unix Lab, which is adjacent to the Math/CS Lab in the basement of Hoyt, is subject to Westminster's Policy for Responsible Use of Information Resources. Specifically:

  1. The Lab exists to serve our students by providing a computing facility in support of their course work and other academic activities. These uses always have priority over recreational use of the facility.
  2. You are responsible for doing your share in keeping the Lab a good place to work. To wit: do not distract or offend others, intentionally or unintentionally, in any way; do not leave trash around; recycle paper. In other words, be a good citizen.
  3. Your login is for your personal use and no one else's. Do not give your password to anyone. If you need to share data with another student, ask us to set up a group for you.
  4. We are all concerned that the hardware be treated properly. Follow any guidelines that are posted near the equipment or that are distributed electronically. Do not try to re-configure any of the equipment, especially the terminals. Do not put food or beverages where they could spill and damage the equipment. You are responsible for anything you damage. It is important to be gentle with the machines even when you are frustrated. Treat them as though you had paid for them and don't be afraid to insist that others do the same.
  5. Another hardware issue is security. Don't let anyone who you don't know personally into the lab; you are responsible for the behavior of your guests in the lab. Be sure that doors are closed and locked when you leave.
  6. Part of your responsibility as a user is to notify us of any hardware problems you encounter. You can contact us by sending mail to problems on keystone or the language machines. Never reboot or power down a machine except under drastic circumstances (water leaking thru the roof onto a machine or a machine burning, etc.). If such an emergency does occur, do what's right for your personal safety and if there is time power the machine off quickly, call 7777 to report the emergency, and contact me, either in the office or at home, regardless of the time.
  7. As a user you must respect the privacy of others. Examples of privacy invasion include reading other people's mail, sending anonymous mail, using accounts other than your own, reading or deleting unprotected files, etc. Help novice users who lack the experience to properly protect their account. We consider data on the disk as real property. As such, finding a file in another user's directory that is readable to the world is like finding a house with the front door unlocked. It is wrong to read that file without invitation from the owner, just as it is wrong to go into a house with an unlocked door and watch TV.
  8. Many of the ``goodies'' out on the network are fun, but not really crucial to your computer science career here. Game playing is acceptable, but has the lowest priority. If the lab is full and you are playing a game, it is your responsibility to recognize the situation and offer your seat to someone who comes in to work.
  9. Finally, feel free to contact us with any computer related problems or questions which occur. Send mail to problems and mention the problem; be sure to include the name of the machine where it happened and how to illustrate or duplicate the problem. The trouble folks won't do homework for you.

Tentative Initial Schedule:

It is your responsibility to read the assigned material before class. What we do in class will not necessarily be what is in the reading.

An actual reading schedule will be determined during/after the first meeting.

Thomas P. Kelliher
Mon Feb 12 17:35:25 EST 1996
Tom Kelliher