FS26 - Distributed Systems (DSy)

This lecture series focuses on distributed systems, which are computer systems made up of multiple autonomous components, or nodes, that are linked and communicate with one another to achieve a common goal.

By the end of the series, you should have a good understanding of the various components and technologies involved in distributed systems and blockchain, as well as their implementation and deployment considerations.

Lecture Topics

The following topics are preliminary and may change or be shifted during the semester.

Online Lectures & Offline Exercises

The Distributed Systems (DSy) lectures will be pre-recorded and uploaded by Friday evening. The length of the videos will be ~ 80 - 100 minutes divided into segments. The news segment (~10 min) will cover news around the topics distributed systems and blockchain and are not part of the exam. It should serve as an overview of current topics in this field. On Mondays, only exercises take place.

I will be in room FZ.0332 from 08:10 - 09:50 in St.Gallen and in room 1.257 from 13:10 - 18:40 in Rapperswil on Mondays. During exercises, you can work on your challenge task. You do not need to be present on Monday, but it is highly recommended to discuss your ideas, issues, and problems with the challenge task. On request, you can also join the exercises remotely via MS Teams.

The online lectures and PDFs can be accessed from outside the OST network (also on Youtube), the exercise and admin material only with VPN.

Lecture

Lecture 1

Lecture 2

Lecture 3

Challenge Task FS 2026

Starting this semester, the challenge task (CT) is individual work. With the availability of generative AI tools, a single student can now design, build, and implement what previously required a group of 2-3. This also means every student must understand the full stack.

This semester's challenge task is the design and implementation of a distributed system (of your choice) from scratch where a service instance can fail. The system needs to have the following components:

1. Simple Frontend (e.g., HTML, Vue, React, Svelte)
2. Load balancer (e.g., Traefik, Nginx, HAProxy, Caddy)
3. Two instances of a service (your choice), and during the challenge task presentation, one instance will be shut off
4. JWT-based authentication (login/registration required to use the application, API endpoints protected with JWT)
5. Database (persistent storage, does not need to be scalable)

Requirements

All requirements below must be met in order to pass this lecture.

1. Load balancing with multiple instances with failover of a service instance
2. Containerized (e.g., with docker)
3. Simple frontend
4. JWT-based authentication
5. Persistent storage
6. Use latest stable releases of chosen libraries and frameworks
7. A fresh clone of the repository + a single command (e.g., docker compose up) must bring up the entire working system (or using Kubernetes), including database seeding/migration if needed. No manual setup steps allowed.
8. Perform a load test against a JWT-protected endpoint of your system (e.g., using ab, wrk, hey, or k6) and document the results. During the presentation, show how your system behaves under load, what the bottleneck could be, and how many requests/second it can handle.

• The use of AI coding assistants (e.g., Claude Code, GitHub Copilot, Cursor, or similar) is highly encouraged. You are expected to understand and be able to explain all code in your project, regardless of how it was produced.
• The solution may use existing libraries and code, but those must be open software software
• You are allowed to use any language, framework, and platforms. However, the supervisors are familiar with those: Java, Golang, JavaScript, Linux.

Milestones

• 02.03.2026 - 1st hand-in of your initial plan and project idea. Invitation to github/gitlab repository
• 30.03.2026 - 2nd hand-in of your initial commit of your challenge task and current progress (initial state, does not need to run)
• 04.05.2026 - 3rd hand-in of your current progress (what works, what is still open)
• 18.05.2026 - final hand-in / presentation
  • You are expected to understand and explain your code
  • Presentations will take place during the week starting 18.05.2026, with slots available throughout the week in both St.Gallen and Rapperswil to accommodate the higher number of individual presentations
  • You should show the architecture, components, and design decisions in 5 min, a demo in 5 min, and the Q&A will be 5 min
  • After your presentation, you need to hand in your PDF presentation.

If all requirements are fulfilled, you are encouraged to hand in before the respective deadlines.

Individual Work

There are no groups this semester. Each student works individually on their challenge task. During exercise hours, you can work on your task and discuss ideas, issues, and problems with the supervisor. You do not have to be present at the exercises, but it is highly recommended. You shall utilize homework time to work on the challenge task besides the exercise time slots. Your submitted source code and presentation will be only accessible via VPN.

For a reference of previous work, go to FS25.