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COEN6731 Winter 2025
Distributed Software Systems

General Information

​Course description​

Welcome to COEN 6731: Distributed Software Systems! Distributed systems form the backbone of many essential services that we rely on every day, from healthcare and banking to financial services and online platforms. 

 

In this course, we will explore foundational concepts in distributed systems, including concurrency, security, fault tolerance, networking principles, remote procedure calls (RPC), peer-to-peer architectures, coordination and agreement protocols, MapReduce frameworks, distributed transactions, and data replication. By understanding these core principles, students will gain the necessary skills to design and build reliable, scalable, and secure distributed applications.

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This year, COEN 6731 will feature a special focus on blockchain technologies, a transformative innovation that is reshaping industries worldwide. We will examine the key building blocks of blockchain systems, with a particular emphasis on consensus mechanisms and fault tolerance. Through this focus, students will gain insights into how blockchain technologies are applied across various domains and understand the challenges of achieving trust and coordination in distributed environments.

​When and where​​

Lectures

  • Time: Wednesday 2:45pm-5:30pm

  • Location: MB 3.445 SGW

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​Teaching staff

Instructor

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Teaching Assistant

General information
Course requirements

Course requirements

Marking scheme

  • Presentations and deliverables (30%)

    • In-class presentation

    • Slides

  • Participation and discussion (10%)​

  • Course project (60%)

    • Proposal​ one pager and presentation (10%)

    • Progress report presentation (5%)

    • Final presentation and demo (20%)

    • Final report (25%)

​Presentation and deliverables

​Complete the form for paper selection preferences and team signup and read the instructions here. ​​​​​​

​Course project

​The description and guidelines of the course project are available here. Submission deadlines are stated below:​​​​​

  • Project proposal report and presentation slides

    • Submit to Moodle by Feb 12, 11:59 pm (lecture day in Week 5).​

  • Progress report​ slides

    • Submit to Moodle by March 12, 11:59 pm (lecture day in Week 8).​

  • Final project report and slides​

    • Submit your slides to Moodle by April 9, 11:59 pm (last lecture).​​​​​

    • Submit your final report to Moodle by April 14, 11:59 pm.

Lecture
Schedule

This is a tentative schedule, which will likely change as the course goes on.

Week 1​

  • Topics: Introductions, fundamentals, and time in DS.

  • Lecture: [Slides]

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Week 2​

  • Topics: Coordination, Agreement, and Paxos 

  • Lecture: [Slides]

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Week 3​

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Week 4 ​

  • Topics: Blockchains, Byzantine fault tolerance (Proof-of-Work and PBFT)

  • Lecture: [Slides​] 

  • PBFT: [Short] [Full]

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Week 5

  • Topics:  Cabinet and demo [Paper]​​

  • Project proposal presentation

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Week 6 (Paper presentations start)​

  • Topics

    • EPaxos [SOSP'13], There Is More Consensus in Egalitarian Parliaments. [Link]

    • NoPaxos [OSDI'16], Just Say NO to Paxos Overhead: Replacing Consensus with Network Ordering. [Link]

    • HovercRaft [Eurosys'20], HovercRaft: Achieving Scalability and Fault-Tolerance for Microsecond-Scale Datacenter Services. [Link]​

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Week 7​

  • Topics

    • HotStuff [PODC'19], HotStuff: BFT consensus with linearity and responsiveness. [Link1] [Link2] Link2 presents an extended version with evaluation results​

    • Pompe [OSDI'20], Byzantine Ordered Consensus without Byzantine Oligarchy. [Link]

    • ResilientDB [VLDB'20], ResilientDB: Global Scale Resilient Blockchain Fabric. [Link]​

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Week 8​

  • Topics

    • Kauri [SOSP'21], Kauri: Scalable BFT Consensus with Pipelined Tree-Based Dissemination and Aggregation. [Link]​

  • Project midterm progress presentations 

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Week 9​

  • Topics

    • Narwhal and Tusk [​Eurosys'22], Narwhal and Tusk: A DAG-based Mempool and Efficient BFT Consensus. [Link]

    • Autobahn [SOSP'24], Autobahn: Seamless high speed BFT. [Link]

    • Chop Chop [OSDI'24], Chop Chop: Byzantine Atomic Broadcast to the Network Limit. [Link]

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Week 10​

  • Topics

    • RBFT​ [ICDCS'13], RBFT: Redundant Byzantine Fault Tolerance. [Link]

    • PrestigeBFT [ICDE'24], PrestigeBFT: Revolutionizing View Changes in BFT Consensus Algorithms with Reputation Mechanisms. [Link]

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Week 11​

  • Topics

    • HoneyBadger [CCS'16], The Honey Badger of BFT Protocols. [Link]​

    • Basil [SOSP'21], Basil: Breaking up BFT with ACID (transactions). [Link]

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Week 12​

  • Final course remarks

  • Final project presentations and demos

Lecture schedule

Course
Policies

Notice of video recording and sharing

At times during this course, some interactions including students’ participation, may be recorded on video. Course videos and materials belong to the instructors, the University, and/or other sources depending on the specific facts of each situation, and are protected by copyright. For questions about recording and use of videos in which you appear please contact your instructor.

Course policies
© 2025 Gengrui (Edward) Zhang
gengrui.zhang@concordia.ca
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