Article 12: Distributed Transactions & Saga Pattern

1. Objective

Learn how to manage transactions across multiple microservices using the Saga pattern.

2. Key Concepts

• Distributed transactions
• Saga pattern
• Compensating transactions
• Eventual consistency

3. Why ACID Transactions Fail in Microservices

• No single database
• Network failures are common
• Services must remain independent

4. Saga Pattern Explained

A saga is a sequence of local transactions where each step publishes an event.

Types of Saga:

• Choreography
• Orchestration

5. Choreography-Based Saga

Order Created -> Payment Service -> Inventory Service
Failure -> Compensation triggered

6. Orchestration-Based Saga

Saga Orchestrator
   |
 Order -> Payment -> Inventory

7. Hands-On Scenario

1. Order created
2. Payment fails
3. Order cancellation triggered as compensation

8. Common Mistakes

• Using Two-Phase Commit (2PC)
• Expecting strong consistency
• Skipping compensation logic

9. Interview Notes

• Saga provides eventual consistency
• Preferred approach in microservices

10. Summary

Distributed transactions require architectural patterns, not database tricks.

11. What’s Next

Move to asynchronous, event-driven communication.