Building a Boring Pub Sub(madrid.rb Feb 2025)

As a proud member of the boringtechnology.club, I want to share with you how we built our own pub sub system for Lingokids.

In this talk, I’ll cover:

- What a pub-sub system is (brief but necessary)
- How we use it at Lingokids (real-world use cases)
- The “less boring” options we considered
- Why we built our own “boring” version (and how we did it)
- The trade-offs and drawbacks of our approach

Expect some code, diagrams, and real production numbers—all wrapped up in a practical, no-nonsense breakdown of what worked (and what didn’t).

Transcript

1. Building a Boring Pub Sub System
2. whoami christos/Χρήστος/[ˈxris̠to̞s̠] – g[r]eek — 1974 / 1982 – 19921998 Academic memory gap – 19992007 "The UK media industry" – 20072017 The Cocktail, jobandtalent, BeBanjo, HOLA.com – Principal Engineer  Lingokids 2017 –
3. Overview Lingokids: The Platform – The Problem – The Solution – Code – Trade-offs – Results and Conclusions –
4. Lingokids The App
6. Lingokids The Iceberg Monolith
8. The Problem
11. Don't be Naive Coupling consider harmful
12. What do you mean by event-driven? 1 https://martinfowler.com/articles/201701-event-driven.html 1.
13. Event-driven Architecture Messaging Patterns
14. In software architecture, publish–subscribe or pub/sub is a messaging pattern where publishers categorise messages into topics that are received by subscribers. This is contrasted to the typical messaging pattern model where publishers send messages directly to subscribers. Similarly, ==subscribers=== express interest in one or more topics and only receive messages that are of interest, without knowledge of which publishers, if any, there are.1 https://en.wikipedia.org/wiki/Publish–subscribe_pattern 1.
16. Avoiding the complexity "brokers" Kafkas, Rabbits, and SQSs
17. Innovation Tokens https://boringtechnology.club
18. Enter Sidekiq From message queue to message broker
19. Boring PubSub Sidekiq + (boring hack)
20. The of a Message Broker Topics → Subscribers
22. The Subscriber Interface
24. The Publisher Interface
26. The Subscriber Implementation
28. The Publisher Implementation
30. The PubSub implementation
33. Trade-offs
34. Trade-offs Out of order delivery
35. Trade-offs Data loss is a possibility
36. Trade-offs At least once delivery semantics
37. Trade-offs Reliability costs $$$
38. Trade-offs One queue, no priorities, memory pressure
39. Conclusion
40. Further reading https://martinfowler.com/articles/201701 event-driven.html – https://boringtechnology.club –
41. Questions?
42. &