One of the biggest problems when dealing with legacy is any change to the software might break the old system. Refactoring is usually slow and dangerous. In this talk I will discuss how we successful migrated an ancient legacy project to an event-driven architecture using just the power of events and Kafka.

1. Confoo 08-03-2018
Moving from legacy to
Event Driven with Kafka
Jeroen van der Gulik

2. About me
❖ Software Architect/ Consultant
❖ Co-Founder Isset
(https://isset.nl)
❖ Señor Developer
❖ Organizer DDDNL
❖ Builder of Artificial Stupidity
❖ @n0x13

7. “The road to hell is paved
with good intentions”

8. Flexibility

9. Security

10. Dependancy

11. Complexity

12. Costs

14. The 5 sins of Legacy
❖ Flexibility
❖ Security
❖ Dependancy
❖ Complexity
❖ Costs

17. “Nothing is more permanent than a
temporary solution”

22. The Project
❖ Proprietary software
❖ Hacked on “solutions”
❖ Old hardware
❖ Business logic in SP: No version control
❖ Original Team members gone
❖ Unwilling supplier

26. The Assignment
❖ Rebuild the Web Portal from scratch
❖ Decouple from the main system
❖ Make the data queryable without causing extra load

27. The Constraints
❖ Cannot change proprietary software easily
❖ Load excessively high: no additional load
❖ Real Time querying not an option
❖ Slow release cycles (quarterly)
❖ Time constraint
❖ Do not jeopardise production

29. Rebuild

30. Refactor

31. Upgrade Hardware

32. Clone Database(s)

33. Strangler Pattern

47. Event-driven architecture (EDA), is a software
architecture pattern promoting the production,
detection, consumption of, and reaction to events.

69. Lessons learned
❖ Events give you a powerful way to decouple
❖ Events are very good contracts
❖ Event driven is a flexible architecture
❖ Making team think in terms of Events can be challenging
❖ Kafka is a very powerful tool but needs research
❖ Mistake are great learning moments
❖ Eventual Consistency is still a hard problem