Class Information

Staff | Course Objectives and Scope | Course Prerequisites | Textbook | Lectures | Grading | Exams | Integrity |

Lorenzo Alvisi
Office: Gates Hall 413a
Phone: (607) 255-4289
Office Hours: M: 17:00-19:00
Teaching Assistants

Course Objectives and Scope

The objective of this course is to introduce you to the key ideas that have shaped distributed computing and are likely to do so in the future; the ambition of this course is to get you as excited about them as I am. The thing about distributed computing that really grabbed me when I first became exposed to it was how its tremendous practical impact was based on beautiful, elegant, theoretical foundations. Because of asynchrony, partial failures, network partitions and concurrency (all issues you'll be an expert on by the end of this course) it is virtually impossible to hack a distributed system into submission: getting it right means being able to prove things about it. This course strives to mirror the multi-faceted nature of the subject it covers. Classes focuses on fundamentals: We will cover problems, models, algorithms, and impossibility results. But to keep ourselves honest, we will integrate the theoretical discussions with substantial projects that will allow to apply some of the concepts discussed in class.
Topics will include the majority (we are going to shoot for all and see what happens) of the following:

Course Prerequisites

The ideal student should have a good undergraduate background in Operating Systems, but, as long as you are willing to learn on demand the OS concepts we will touch upon, (and I'll be happy to give you pointers on how to do that), you should be fine.
So, what are the real hard pre-requisites? The first is to be willing to participate in class. I like to make the class interactive---and for that, I need you. Second, you need to be willing to get in touch with your inner Ninja, both on the theoretical and systems side. You should either be (or be willing to become) comfortable about developing proofs, as several of the homework problems will require you to develop protocols and prove them correct. The course programming assignments, in turn, will require you to either be familiar, or learn as you go, the rudiments of network programming.


There is no required textbook for this class. (Thank you, thank you). Instead, you will be required to complete reading assignments centered on research papers that will integrate what we will be discussing in class. I will also make available my class notes---I'll do this after class (typically at the end of the week), because I want you to think about the question I'll be asking "live", rather than reading the answers in my notes!

If you want to purchase a book for you to keep as a reference, there are several to choose from:


MW: 19:30-20:45, Philips 101

Notable dates in the schedule

The University's official website will continue to report the exam as on December 15 (the original date that had a conflict with the Recognition Event for December graduates). Don't be confused: the exam is on December 8, at 7:00 pm.

A note about email

I would like to discourage you from contacting me by email with substantive technical questions; instead, I would like to encourage you to come see me in person during office hours, asking for an appointment outside of them if necessary, to discuss questions you may have about the material. There are two reasons for why I strongly discourage you from having a technical conversation by email: 1) DOS defense. As you know, a one-line email may require several pages of explanations back: a perfect Denial of Service attack! The problem is that the attacker (you :-) ) can at very low cost for himself cause the server (me) to perform an unbounded amount of work. A strategy to counter denial of service is to structure protocols so that a potential attacker must perform approximately the same amount of work as the server: if the question is important enough to require 30 minutes of my time, then it should justify at least 30 minutes of yours. 2) It may sound cheesy, but I want to get to know you, and you visiting my office is the best way for me to accomplish this.


It is important for you to realize what grades in this class reflect and what they don't reflect. All we can grade you on is how well you demonstrate that you know the material this semester. We can't grade you on how much of a success you'll be after graduation, how smart/creative/persistent/self-motivated you are, or even how well you'll be able to apply the material in the future. And after all, it is what you do in the future, not what you do this semester, that's really important.

That said grades will be determined as follows:

Exams (2)

50% (20%/30%)

Homework (3)


Projects (3)


Extracredit (course eval)


Projects will be of different complexity, which will be reflected in the percentage of credit that each will earn.


In some courses, the TAs and instructor have to spend a lot of time dealing with re-grading appeals, time that would be better spent helping students learn the material. Absolutely come to us if we make an arithmetic error, but realize that a few points here and there are extremely unlikely to make any difference in your final grade. If you believe that we assigned too little credit for your work, you may submit your work for a re-grade under the following restrictions. (1) All re-grade requests must be submitted with a clear, written statement that explains why you believe the original grade was incorrect. (2) All requests for re-grades must be submitted within 1 calendar week of when the graded work is returned. (3) We will truly re-grade the entire exam, problem set, or project assignment, not just the issue you bring to our attention. So, to be clear: if in the process we find out other issues that had escaped us the first time, we will deduct points. Thus, you grade can go up or down on a re-grade.

Academic Integrity

You are encouraged to work in groups on the programming projects; you may form a different group for each programming project.

Groups should comprise 1 to 3 students. Groups of size 2 or 3 are ideal for the kinds of projects you will undertake. Working with other people not only can lead to a better understanding of the material but it will enable you to develop collaboration skills that should prove helpful throughout your career. Each participant in a group should be able to explain the entire content of any submitted solution.

Students are required to work alone on the written assignments.

Violations of the Cornell University Code of Academic Integrity will be prosecuted aggressively. Collaborate with other members of your group on the project; do not collaborate with anyone (within your group, outside of your group, on the Internet, whether synchronously or asynchronously) on other homework. Looking on line for solutions to problem set questions (even those buried in research papers not assigned as readings) will be very much considered a violation of the Code of Academic Integrity. Students are also expected to be familiar with the University's and the CS Department's various policies on appropriate use of computers.


Class attendance (or lack thereof) does not directly reflect into credit: however, it is my experience that students who don't attend class tend not to do well. "Duh" you might say---but again, coming to class is truly critical for your success in this class, especially considering that this class does not follow a textbook. I will occasionally have a roll call at the beginning of class-again, absence or presence has no effect on credit: but I would like to get to know you by name, and I am terrible with names, so I hope this will help me.


The midterm will take place in class on October 10. I do not know at this time when the final will take place.

Once the date of the final is posted, if you have a conflict with the date of the final, please inform the instructor within two weeks. After this date, conflicts will be considered if they are caused by either:

  1. Illness, which has to be documented by a doctor and approved by the university.
  2. Death in the immediate family.

Late policy. No extensions will be given for completing the homework or the programming projects, except that students will be allowed 6 flexible slip days for the projects and homework during the semester. A student may divide slip days across projects in any way he or she wishes to extend deadlines for the projects (or a homework) except for projects or homework due at end of the semester. To help your TAs track your slip-day status, the top of your project README file (or your homework) should include the line:

Please not that: Slip days will be tracked at the granularity of a day; if an assignment is 1 minute late, it is one day late: this is not to be draconian, but to show some respect for your TA. If two project partners have different numbers of slip days remaining on their accounts, the slip days account for the team is the min of the partners' slip day balances.
Exemptions of the above rules will be allowed in two cases:
  • Illness, which has to be documented by a doctor and approved by the university.
  • Death in the immediate family.
  • Special Accommodations

    If you have a disability-related need for reasonable academic adjustments in this course, please provide an accommodation notification letter from Student Disability Services. Students are expected to give two weeks’ notice of the need for accommodations. If you need immediate accommodations or physical access, please arrange to meet with me within the first two class meetings. The website for Student Disability Services is:

    This page is maintained by Lorenzo Alvisi. Last updated August 18, 2016