CPSC 426/526: Building Decentralized Systems, Fall 2013 [an error occurred while processing this directive] — Overview

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  • Administrative
  • Overview
  • Reference Materials
  • Computers
  • Grading
  • Collaboration Policy
  • Attendance
  • Keeping In Touch

  • Administrative Information

    MW 1:00-2:15 PM, Room 200 AKW

    Bryan Ford, Room 411 AKW, 432-1055
    Office hours: Mon & Wed 2:30-3:30 PM, or by appointment.

    Teaching Assistant:
    Ennan Zhai, Room 404 AKW, 415-5957
    Office hours: Tue & Thu 2:30-4:30 PM, or by appointment.
    (Ennan will be in the office (not zoo) during the office hours.)

    URL: http://zoo.cs.yale.edu/classes/cs426/2013


    This course explores practical principles and techniques for building decentralized systems.

    What is a decentralized system? Basically, a distributed system that works although no one is in charge.

    For purposes of this course, a distributed system is a set of computers that are physically distributed but can communicate via some form of network. A decentralized system is a particular kind of distributed system: namely, a set of computers that are under the control of multiple separate owners or administrative authorities, not just one, who wish to use their networked computing facilities to communicate, organize, or share computing resources, even if not all the machines' owners are guaranteed to trust or “play nicely” with each other. The course takes a hands-on approach, emphasizing learning by doing.

    Lectures: The course's lectures will present and discuss challenges, known techniques, and open questions in decentralized system design and implementation. Lectures will often be driven by examination of real decentralized systems with various purposes in widespread use the past or present, such as UseNet, IRC, FreeNet, and Tor. Throughout the course we will explore fundamental security and usability challenges such as decentralized identification and authentication, denial-of-service and Sybil attacks, and maintenance of decentralized structures undergoing rapid changes (churn).

    Labs: During the semester, students will develop a small but usable peer-to-peer communication application that reflects a few of the important design principles and techniques to be explored in the course, such as gossip, social trust networks, distributed hash tables, and byzantine consensus algorithms. The labs will designed so that solutions can initially be tested individually on private, virtual networks running on one machine (e.g., a zoo machine), then tested collectively by attempting to make different students' solutions interoperate on a real network.

    Course Materials: There is currently no formal textbook for this course. The Internet is your textbook. We will offer informal lecture notes, various reading assignments, and pointers to relevant information on the Web: see the schedule and the reference page in particular. Beyond these informal materials, you will be expected to exercise—and sharpen—your “information scavenging” skills and creativity in order to figure out how to accomplish the tasks you are assigned. Although you are not required to buy any textbook for this course, you may find it very useful to have on hand, or reference in the library, one or more standard distributed systems textbooks such as:

    Course Prerequisites: CS 323 Introduction to Systems Programming and Computer Organization, or with CS 426 instructor's permission, comparable C/C++ systems programming experience.

    Course Outline

    This course is still under development and all parts of the syllabus should be viewed as tentative and subject to change. See the schedule page for details, but covered topics are likely to include:


    You will be using the Intel Linux PCs in the Zoo computing lab. You may access them either locally on the third floor of Watson Hall, or remotely via the following command, which will log you into a randomly-chosen Zoo machine in order to balance load on the cluster:
    	ssh netid@node.zoo.cs.yale.edu

    To access these PCs, you can either directly login from their consoles in the Zoo, or just remotely login from other machines across the campus.

    If you plan to take the course for credit, you should get an account on these machines in the first week. Please also visit the following web site to create a cs426 class directory (or just to sign up for a zoo account):


    Do not allow anyone else to use your accounts for any purpose. They are for your use alone, and you are responsible for any misuse. Your passwords control access to your accounts and should be kept secret.

    Course Structure and Grading

    The above weights are subject to minor adjustments during the semester.

    Collaboration Policy

    Programming, like composition, is an individual creative process. Individuals must reach their own understanding of the problem and discover a path to its solution. During this time, discussions with friends are encouraged. However, when the time comes to write the code that solves the problem, such discussions are no longer appropriate: each student's code must be the work of the members of that student alone (although you may ask teaching assistants or lab assistants for help in debugging). In your coding you are encouraged to adopt ideas suggested by classmates or other reference sources, but must carefully acknowledge the sources of those ideas in your own code and/or documentation.

    Do not, under any circumstances, copy another student's code. Writing code for use by another or using another's code in any form violates the University's academic regulations and will be dealt with harshly.

    Academic integrity is a core institutional value at Yale. It means, among other things, truth in presentation, diligence and precision in citing works and ideas we have used, and acknowledging our collaborations with others. In view of our commitment to maintaining the highest standards of academic integrity, the Graduate School Code of Conduct specifically prohibits the following forms of behavior: cheating on examinations, problem sets and all other forms of assessment; falsification and/or fabrication of data; plagiarism, that is, the failure in a dissertation, essay or other written exercise to acknowledge ideas, research, or language taken from others; and multiple submission of the same work without obtaining explicit written permission from both instructors before the material is submitted. Students found guilty of violations of academic integrity are subject to one or more of the following penalties: written reprimand, probation, suspension (noted on a student’s transcript) or dismissal (noted on a student’s transcript).

    Lab Handin Procedures

    You will be using the Git version control system to manage source code in your programming labs and to hand in assignments, as will be laid out in Lab 1.


    Attendance at lectures is expected but will not be recorded. Students are, however, fully responsible for all material presented in lectures, even if some of it does not appear in the "official" lecture notes. Class attendance is recommended strongly.

    Lecture notes will be made available, though they are by no means guaranteed to be a complete record of the class and cannot substitute for class attendance.

    Keeping In Touch

    The best way to contact the instructor and the TA is by electronic mail. To get help quickly, your best bet is to send email to cs426ta@cs.yale.edu, where it will be seen only by the instructor and TA, or to cpsc426_f13@classesv2.yale.edu, where your message will also be forwarded to every student in the class. Use of the whole-class mailing list is encouraged especially in the case of clarifications or debugging questions, since it is likely that other teams will be encountering the same or similar difficulties that you are and may offer the quickest answer. All the course-related information will be kept on the web (URL: http://zoo.cs.yale.edu/classes/cs426).

    Copyright (c) 2000-2010 Bryan Ford, Department of Computer Science, Yale University