Event Driven Workflows - Andrew Wormald, Luno

Event-driven workflows help break down complex business logic into sequential steps while maintaining deterministic behavior and process visualization

The solution uses a directed acyclic graph (DAG) approach, meaning workflows can only move forward and cannot revisit previous nodes

Built with interfaces for data storage and event streaming, allowing flexibility to use different technologies (Kafka, RabbitMQ, Reflex) through adapters

Provides built-in support for:

• Timeouts and scheduling (cron)
• Parallel processing
• Role-based sharding
• Process visualization (Mermaid diagrams)
• Test helpers and acceptance testing

Uses the outbox pattern for handling events, providing strong consistency but with some latency tradeoff

Focuses on idempotency - consumers should be idempotent to handle duplicate events safely

Supports GDPR compliance through data deletion capabilities while maintaining workflow history

Designed to work with existing infrastructure rather than requiring new systems/services

Currently in production use at Luno for critical paths like customer onboarding and payment processing

Core design goals:

• Sequential processing
• Distributed architecture
• Loose coupling
• Scalability
• Process visualization
• Complex business logic handling