6.2 Using Events to Maintain Data Consistency Event Driven Microservices

 April 4, 2021

Event-driven order processing 

Eventually consistent credit checking 

Place order, order created, credit reserved, or credit check failed 

Order management   customer management 

Problem #1: How to design eventually consistently? 

Problem #2: How atomically update database and publish an event 

Failure = inconsistent system 

Order service 

Update and publish using 2PC 

• Guaranteed atomicity BUT
• Need a distributed transaction manager
• Database and message broker must support 2PC
• Impacts reliability
• Not fashionable
• 2PC is best avoided