Safely Handling Side Effects in Distributed Systems

In distributed systems, external side effects like emails or payments cannot easily be rolled back — classic synchronous transactions and so‑called two‑phase commits quickly hit their limits.

This training shows how to decouple decisions from executing side effects and how to build robust, auditable flows using the Outbox/Inbox patterns, idempotency, and sagas.

The result: simpler fault tolerance, clear responsibilities, and reliable business processes across service boundaries.

• Why two‑phase commits (2PC) often fail in practice
• Event‑based decoupling: decision vs. side effect
• Putting the Outbox pattern into practice
• Inbox pattern and idempotency: safely handling duplicate events
• At‑least‑once delivery: detect duplicates and process them correctly
• The Saga pattern: compensation instead of rollback

This training is for backend developers and software architects who want to implement distributed business processes robustly — from event sourcing and CQRS to microservices.

Ideal for teams integrating external systems while ensuring consistency, idempotency, and traceability.

Basic knowledge of relational databases and PHP is recommended.

Experience with messaging/event systems is helpful but not required.

• You'll separate decisions from side effects to increase process reliability
• You'll implement Outbox and Inbox in practice and make your handlers idempotent
• You'll confidently handle at‑least‑once delivery and duplicates
• You'll model sagas with compensations — without 2PC and without ACID expectations