Administrative Information

Professor

T.A.

Course Description

Distributed systems consists of a collection of independent computers that appears to its users as a single coherent system. While their early development followed the emergence of high-speed local area computer networks at the beginning of 1970s, the recent availability of powerful and cheap microprocessors and pervasive connectivity has brought the topic to everyone's attention.
In this course we will discuss some of the basic principles behind distributed systems and review some of the main paradigms used to organized them.

Location and Time

Tuesdays and Thursdays - 2:00-3:20PM, place Ford SB-340.

In compliance with Section 504 of the 1973 Rehabilitation Act and the Americans with Disabilities Act, Northwestern University is committed to providing equal access to all programming. Students with disabilities seeking accommodations are encouraged to contact the office of Services for Students with Disabilities (SSD) at +1 847 467-5530 or ssd@northwestern.edu. SSD is located in the basement of Scott Hall. Additionally, I am available to discuss disability-related needs during office hours or by appointment.

Course Prerequisites

• EECS-343 Operating Systems (or equivalent)
• EECS-340 Introduction to Networking.
• (Please contact me if you do not meet some of these requirements, but feel you are prepared to take the course.)

Communication Channels

There will be a number of communication channels set up for this class:

• We will use the course web site (http://www.aqualab.cs.northwestern.edu/classes/eecs-345-w08) to post announcements related to the course. You should check this regularly for schedule changes, clarifications and corrections to assignments, and other course-related announcements.
• There will be a newsgroup (cs.345 at news.cs.northwestern.edu) to foster communication outside the classroom.
• There will be an email alias ( eecs-345-ta@cs) for the staff that you should use for questions that would be inappropriate to post on the newsgroup/discussion-board.

Announcements

Remember to check this regularly!

• The project handout is posted!
• Homework 2 is posted; it goes from synchronization to security (only 4 questions).
• Homework 1 is finally posted; it covers from Introduction to Naming, included.
• Please note the update on the homework dates to account for changes in the schedule.
• On Thu. 1/24 Dave will give a brief intro on how to use PlanetLab.
• Note the changes to the schedule to make up for the lost class.
• Today (Thu. Jan. 10th) we'll be meeting in Ford SB360. Note that we will cover the first topic and paper (Grapevine).

Materials

Required

• Andrew S. Tanenbaum and Maarten van Steen. Distributed Systems: Principles and Paradigms. Prentice Hall, 2nd Ed., 2006 ("DSP2" from now on).
• A set of research papers I will make available (see the schedule page for a full list).

Course Organization

The course is organized as a series of lectures, homework assignments, a single term-long project and a take-home exam. During lectures, we will cover introductory material during the first 50' and discuss a related seminal paper during the last 30'.

• Lectures - A set of lectures on the core of the material.
• Readings - Textbook and paper reading in preparation for (not subsitution of) the lecture.
• Project - A major project that addresses issues, solve problems and exploit techniques from classroom discussions and readings.
• Homework - A set of homework assignments aimed at reinforcing the material covered in the reading and the lectures.
• Exam - A take-home, final given in the last week of class.

Reading Papers

When reading papers it is normally useful to write down a summary of about a page. Your summary should include at least:

1. Paper title and its author(s).
2. Brief one-line summary.
3. A paragraph of the most important ideas: perhaps a combination of their motivations, observations, interesting parts of the design, or clever parts of their implementation.
4. A paragraph of the largest flaws; maybe an experiment was poorly designed or the main idea had a narrow scope or applicability. Being able to assess weaknesses as well as strengths is an important skill for this course and beyond.
5. A last paragraph where you state the relevance of the ideas today, potential future research suggested by the article, etc.

You may find the following brochure useful: Efficient reading of papers in Science and Technology by Michael J. Hanson, 1990, revised 2000 Dylan McNamee.

Project

There will be one single project on which you will work throughout the quarter. As part of this project you will develop a simple monitoring service for distributed systems including a visualization tool for it. Scalable system monitoring is a fundamental abstraction for large-scale distributed systems. It serves as basic building block for a variety of applications -- from financial services to online gaming. You will do your work in PlanetLab (www.planet-lab.org), a global-scale testbed for distributed systems experimentation consisting of over 800 nodes.

Homework

There will be two kinds of homework assignments given throughout the class: paper reading assignments and textbook-style questions. You should have finished reading the assigned paper before coming to lecture. In addition, there will be a set of written homework assignments inteded to ensure that you keep up with the reading. Each assignment will consist of about 3 short questions, to be done alone and turned in by midnight on the due date (see course policies below).

Homework	Out	In	Solution
1: From motivation to naming	02/04	02/12
2: From synchronization to security	03/06	03/13

Exams

There will be a take-home, final given in the last week of class.

Grading

I use a criterion-referenced method to assign your grade; in other words, your grade will be based on how well you do relative to predetermined performance levels, instead of in comparison with the rest of the class. Thus, if a test has 100 possible points, anyone with a score of 90 or greater will get an A, those with scores of 80 or greater will get a B, those with scores of 70 or greater will get a C, and so on. Notice that this means that if everyone works hard and gets >90, everyone gets an A.

Total scores (between 0 and 100) will be determined, roughly, as follows:

• Homework and reading assignments 20%
• Class participation 10%
• Project 45%
• Exam 25%

Topics

• Introduction: Defining distributed systems and their goals, hardware and software concepts, the client-server model and architecture, modern architectures for distributed systems.
• Wide-area dsitributed systems and PlanetLab: Issues with wide-area distributed systems and brief introduction to PlanetLab.
• Communication: Basics of communication, remote procedure calls, remote object invocation, message-oriented and stream-oriented communication.
• Processes: Clients, servers, code migration and software agents.
• Naming: Naming and locating entities, removing unreferenced entities.
• Synchronization: Synchronization in distributed systems, logical time, global state, elections and mutual exclusion.
• Consistency and replication: Data replication, scalability, and consistency
• Fault tolerance: Making distributed systems fault tolerant, reliable and resilient multicasting.
• Security: Secure communication and authorization in distributed systems.
• Review of major distributed systems paradigms: Distributed object systems (Corba, Globe, ...), Distributed file systems (Plan 9, XFS, SFS, ...), Distributed document-based systems, and Distributed coordination-based systems.