The implementation of microservice architecture using kafka as event-store. Most of the business logic implemented by Kafka Streams stateful operations. All components communicate via events in kafka topics.
Order service provides a REST API for creating and getting orders with CQRS style. It has local kafka-streams based local store and two type or get queries: get current order state by id and long-pooling get order, which will wait until order will be validated by other services.
Orders are validated in parallel by 3 validation services: Fraud, Order details and Warehouse services. After validation has been completed Validations-aggregatos-service aggregate the result and decide if order pass or not validation.
Architecture is described in the great book - Designing event-driven systems by Ben Stopford
System Architecture:
image source
- order-service
- fraud-service
- order-details-service
- order-validations-aggregate-service
- order-history-service
- warehouse-service
For local development run LocalRunner which will start kafka and kafka ui via testcontainers.
To simulate store customers run ClientSimulation