Announcements

Remember to check this regularly!

• Take the tour – http://tour.golang.org
• Piazza for DS
• Canvas' site for the course

Catalog Description

Basic principles behind distributed systems (collections of independent components that appear to users as a single coherent system) and main paradigms used to organize them.

Course Prerequisites (NOTE CHANGES)

• EECS-213 Intro to Computer Systems
• EECS-214 Data Structures and Data Management
• (Please contact me if you do not meet some of these requirements.)

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 This email address is being protected from spambots. You need JavaScript enabled to view it. . SSD is located in the basement of Scott Hall. Additionally, I am available to discuss disability-related needs during office hours or by appointment.

Distributed systems are collections of networked computers that coordinate their actions through message exchanges. Most computing systems you interact with everyday are indeed distributed (e.g. email, the Web, Google, Skype, Facebook ...) for a variety of reasons such as fault tolerance, performance, and the geographical nature of the requirements.

In this course, we will discuss some of the basic principles behind distributed systems as well as common approaches and techniques used to build them. We illustrate these ideas through case studies of widely used or seminal systems.

Some of the topics covered

• Remote invocation and indirect communication
• Time and coordination
• Overlay networks and P2P
• Distributed storage and file systems
• Name services
• Global state and transactions
• Replication and consistency
• Consensus
• Fault tolerance
• Security and privacy

Communication Channels

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

• We will use the course web site 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.
• We will use Piazza for class discussion. The system is highly catered to getting you help fast and efficiently from classmates, the TA, and myself. Rather than emailing questions to the teaching staff, I encourage you to post your questions on our Piazza for DS
• There is always email for questions that would be inappropriate to post on the newsgroup/discussion-board. When using email to contact the staff please start your subject line with "eecs345: helpful-comment" to ensure a prompt response.

Course Organization

The course is organized as a series of lecture and paper discussions, four projects and a take home exam.

• Lectures - A set of lectures on the core of the material.
• Readings - Textbook and paper reading in preparation for (not substitution of) the lecture.
• Homework assignments - A set of assignments meant as reader enforcers.
• Projects - Four programming projects to give you a better understanding of the subject matter and experience with the Go programming language.
• A final exam.

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 (90-93: 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 >93, everyone gets an A.

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

• Homework assignments 15% (+5% extra paper-related questions)
• Class participation 10%
• Projects 50%
• Exam 25% (+5% extra on paper-relatex questions)

Policies

Late policy:

Unless otherwise indicated, homework assignments and projects are due by midnight on their due date. If you hand in an assignment late, we will take off 10% for each day (or portion thereof) it is late. Assignments that are three or more days late receive no credit.

Cheating vs. Collaboration:

Collaboration is a really good thing and we encourage it. On the other hand, cheating is considered a very serious offense. When in doubt, remember that it's OK to meet with colleagues, study for exams together, and discuss assignments with them. However, what you turn in must be your own (or for group projects, your group's own) work. Copying code, solution sets, etc. from other people or any other sources is strictly prohibited.

UNDER CONSTRUCTION BASED ON 2018 SCHEDULE

The following is our intended calendar with topics, slides (as they become available) and reference material. Note "CDKB5 #" refers to chapters of the class' textbook (Coulouris et al., Distributed Systems: Concepts and Design, 2012). Papers, except when tagged as [reference], may be part of homework assignment/finals questions.

Week	Date	Topic
1	4/3	Introduction [PDF] References: CDKB5 1, 2 Google’s Introduction to Distributed System Design Dean and Ghemawat, MapReduce: Simplified Data Processing on Large Clusters, OSDI 2004
	4/4	Networking [PDF] References: CDKB5 3, 4 D. Clark, The design philosophy of the DARPA Internet Protocols, SIGCOMM 1988
2	4/9	Communication - RPC/RMI [PDF] References: CDKB5 5 A. Birrell and D. Nelson, Implementing Remote Procedure Calls, ACM ToCS, 2(1), Feb. 1984
	4/11	Indirect communication [PDF] References: CDKB5 6 Google, Google Cloud Pub/Sub: A Google-Scale Messaging Service A. Demers, et al., Epidemic Algorithms for Replicated Database Maintenance, PODC, 1987
3	4/16	Time and Synchronization [PDF] References: CDKB5 14.1-14.4 D. Mills, Internet Time Synchronization: the Network Time Protocol, Transactions on Communications, 1991 M. Raynal and M. Singhal, Logical time: Capturing causality in distributed systems, IEEE Computer, 29(2), Feb. 1996
	4/18	Global State [PDF] References: CDKB5 14.5-14.6 M. Chandy and L. Lamport, Distributed Snapshots: Determining Global States of Distributed Systems, ACM TOCS, Feb. 1985
4	4/23	Coordination I [PDF] References: CDKB5 15.1-15.4 P. Hunt et al., ZooKeeper: Wait-free coordination for Internet-scale systems, USENIX ATC 2010 H. Garcia-Molina, Elections in Distributed Computer Systems, IEEE ToC, C-31(1), 1982
	4/25	Coordination II [PDF] References: CDKB5 15.1-15.4 Kaashoek et al.,An efficient reliable broadcast protocol, ACM SIGOPS 23(4), 1989. Birman et al., Reliable communication in the presence of failures,, ACM TOCS 5(1), 1991
5	4/30	Consensus [PDF] References: CDKB5 15.5 D. Ongaro and J. Ousterhout, In Search of an Understandable Consensus Algorithm, USENIX ATC 2014 Fisher, Lynch, Patterson, Impossibility of Distributed Consensus With One Faulty Process, JSAC, 1985 [ref]
	5/2	Consensus [PDF] References: CDKB5 15.5 D. Ongaro and J. Ousterhout, In Search of an Understandable Consensus Algorithm, USENIX ATC 2014 Fisher, Lynch, Patterson, Impossibility of Distributed Consensus With One Faulty Process, JSAC, 1985 [ref]
6	5/7	No lecture
	5/9	Transactions and Distributed Transactions [PDF] CDKB5 16-17 J. Corbett et al., Spanner: Google's Globally-Distributed Database, OSDI 2012 A. Dragojevic et al., No compromises: distributed transactions with consistency, availability, and performance, SOSP 2017
7	5/14	Transactions and Distributed Transactions [PDF] CDKB5 16-17 J. Corbett et al., Spanner: Google's Globally-Distributed Database, OSDI 2012 A. Dragojevic et al., No compromises: distributed transactions with consistency, availability, and performance, SOSP 2017
	5/16	Replication and consistency [pdf] References: CDKB5 18 E. Brewer, CAP Twelve Years Later: How the "Rules" Have Changed, IEEE Computer, 2012 D. Terry et al., Managing Update Conflicts in Bayou, a Weakly Connected Replicated Storage System, SOSP 1995
8	5/21	Replication and consistency [pdf] References: CDKB5 18 E. Brewer, CAP Twelve Years Later: How the "Rules" Have Changed, IEEE Computer, 2012 D. Terry et al., Managing Update Conflicts in Bayou, a Weakly Connected Replicated Storage System, SOSP 1995
	5/23	Distributed File Systems [pdf] References: CDKB5 12 A. Muthitacharoen, B. Chen and D. Mazieres, A Low-bandwidth Network File System, SOSP 2001 R. Sandberg, D. Goldberg, S. Kleiman, D. Walsh and B. Lyon, Design and Implementation of the Sun Network File System, USENIX 1986 [ref] J. Howeard, M. Kazar, S. Menees, D. Nichols, M. Satyanarayanan, R. Sidebotham and M. West, Scale and Performance in a Distibuted File System, ACM ToCS, 6(1), 1988 [ref]
9	5/28	Memorial Day
	5/30	Distributed Storage [pdf] References: CDKB5 12 S. Ghemawat et al., The Google File System, SOSP 2003. F. Chang et al. BigTable: A Distributed Storage System for Structured Data OSDI 2006
10	6/4	Name Services and Content distribution networks [pdf] References: CDKB5 13, 10, 20.6 P. Mockapetris and K. Dunlap, Development of the Domain Name System, SIGCOMM 1988 C. Huang et al., Measuring and Evaluating Large-Scale CDNs, (withdrawn) IMC 2008 M. Zhao et al., Peer-Assisted Content Distribution in Akamai NetSession, IMC 2013 [ref]
	6/6	Overlay Networks [pdf] References: CDKB5 4.5, 10 I. Stoica et al., Chord: A Scalable Peer-to-peer Lookup Service for Internet Applications, SIGCOMM 2001 P. Maymounkov and D. Mazieres, Kademlia: A Peer-to-peer Information System Based on the XOR Metric, IPTPS 2002 BitTorrent "trackerless" torrents [ref]
*	6/11	Final

Assignments

There are four projects and some basic homework assignments, mostly meant as reading eforcers, and four team-projects that build on each other.

We will post all asignments in the Canvas' site for the course.

Projects

This year you will build two large systems, a mapreduce library and a replicated state machine protocol. Each effort is divided into two projects for a total of four projects. Projects are to be done in teams of 2-3 students (1 is not allowed).

All projects will be done in Go, a language that was originally created within Google, but is now a fully open-source project. Go is garbage-collected and has built-in coroutines (called goroutines) and channels, making it highly suited to building distributed systems. Its standard library is already pretty comprehensive. For example, take a look at the net and rpc packages.

Calendar of assignments

Reading Papers

We will be reading two or more paper per week; you should have read the assigned paper before coming to lecture.

When reading papers it is 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 documents useful:

• How to Read a Paper by S. Keshav, ACM SIGCOMM CCR, 37(3), 2007.
• Efficient reading of papers in Science and Technology by Michael J. Hanson, 1990, revised 2000 Dylan McNamee.

Materials

Required

• George Coulouris, Jean Dollimore, Tim Kindberg and Gordon Bair, Distributed Systems: Concepts and Design.Pearson, 5th Ed., 2012 ("CDKB5").
• A set of research papers I will make available (see the schedule page for a full list).

Very Useful

• S. Keshav, How to Read a Paper, ACM SIGCOMM CCR, 37(3), 2007.
• Michael J. Hanson, Efficient reading of papers in Science and Technology, 1990 (revised 2000 Dylan McNamee).
• Roy Levin and David D. Redell, An evaluation of the ninth SOSP submissions -or- How (and how not) to write a good systems paper, ACM SIGOPS Operating Systems Review 17(3):35-40 (Jul., 1983)
• George D. Gopen and Judith A. Swan,The Science of Scientific Writing,American Scientist (Nov-Dec 1990), 78: 550-558.