Journey of saga pattern in microservice architecture
- 1. Journey of SAGA pattern in Micro-service Architecture Presented by Anisur Rahman 9:26 AM
- 2. Refactoring Monolith to Micro-services Two refactoring strategies: Strategy 1: Implement new functionality as services Strategy 2: Extract services from the monolith 5 Steps: Step 0: Review AS-IS code Step 1: Split the code Step 2: Split the database Step 3: Define a standalone “Delivery service” Step 4: Use the standalone “Delivery service” Step 5: Remove the delivery management functionality from the FTGO monolith 9:26 AM
- 3. Strategy 1: Implement new functionality as services Story Micro Service Micro Service Micro Service Database Database Database 9:26 AM
- 4. Strategy 2: Extract services from the monolith 9:26 AM
- 5. Review codebase, client- domain interaction, database Step 0: Review Monolith code 9:26 AM
- 6. Step 1: Split the code Convert delivery management into a separate, loosely coupled module within the monolith 9:26 AM
- 7. Step 2: Split the database Split the database and define a separate database schema for the Delivery service module 9:26 AM
- 8. Step 3: Define a standalone “Delivery service” Just define a standalone service but don’t use it 9:26 AM
- 9. Step 4: Use the standalone “Delivery service” Start using that standalone service 9:26 AM
- 10. Step 5: Remove the delivery management functionality from the FTGO monolith Remove Delivery related code from Order Management Service 9:26 AM
- 11. Maintain data consistency in Micro service Architecture 2PC Event Sourcing SAGA 9:26 AM
- 12. Need to know ACID transaction before SAGA (recap) Atomicity: Transaction either completes fully or fails completely. Consistency: Maintain the logical consistency, no matter of its final outcome. Isolation: Multiple transactions occur concurrently without causing inconsistency of database state Durability: Durability means that committed transactions remain committed irrespective of any type of system failure. 9:26 AM
- 13. What is SAGA? A pattern that maintain data consistency across services using a sequence of local transactions that are coordinated using asynchronous messaging. Maintain data consistency Sequence of local transactions. Each local transaction updates data within a single service using the ACD transactions. Asynchronous messaging occur in SAGA 9:26 AM
- 14. SAGA Lets see an example to understand the SAGA pattern & its characteristics: Make Order Create Order Update inventory Regular shopping Return Order Status 9:26 AM
- 15. SAGA implementation 2 ways are most popular to implement SAGA: SAGA — Choreography Event based Each service communicate with each other via Message Broker SAGA — Orchestration Command based Orchestrator is own a service Each service communicate with Orchestrator 9:26 AM
- 16. SAGA - Choreography Order Service Inventory Service Shipping Service Inventory DB 9:26 AM
- 17. SAGA – Choreography - Rollback Order Service Inventory Service Shipping Service Inventory DB 9:26 AM
- 18. SAGA – Orchestration Inventory Service Inventory DB 9:26 AM
- 19. Inventory Service Inventory DB SAGA – Orchestration – Rollback 9:26 AM
- 20. Really why you need Orchestration? 3 main reasons I found through my R&D: A second transaction willing to change the same target object, you can easily put it on hold on the orchestrator until the first transaction ends. (Isolation problem solved) Easier rollback management Either I use Choreography OR Orchestration, I must have to create a SEC. So, in Orchestration the Orchestrator act as a SEC. This gives me more flexibility. SEC will maintain Audit log. If I use SEC in Choreography then it will create a Event Sourcing Anti Pattern. How can Choreography maintain Isolation? Use Counter measure design pattern: Semantic lock + Saga status 9:26 AM
- 21. When need to apply Rollback mechanism? Two type of error can occur through SAGA pattern: Technical Error: Reasons to occur: Database Connection Lost, Service down for any reason, Code level Bug Solution: Use Message Broker for RETRY mechanism Business Error: Reasons to occur: Business rules violation Solution: Apply Compensate transactions 9:26 AM
- 22. Next Topic Message Broker (RabbitMQ) 9:26 AM