Food ordering system

This system has four main microservices which are mainly following event-driven architectural patterns.

• Order-Service.
• Payment-Service.
• Restaurant-Service.
• Customer-Service.

How to run the services?

You need docker to run the application. Run below scripts respectively:

• infrastructure/docker-compose/start-zookeeper.bat
• infrastructure/docker-compose/start-kafka.bat
• infrastructure/docker-compose/init-kafka.bat

Then run below main classes:

• order-service/order-container/src/main/java/com/food/ordering/system/order/service/domain/OrderServiceApplication.java
• payment-service/payment-container/src/main/java/com/food/ordering/system/payment/service/domain/PaymentServiceApplication.java
• restaurant-service/restaurant-container/src/main/java/com/food/ordering/system/restaurant/service/domain/RestaurantServiceApplication.java
• customer-service/customer-container/src/main/java/com/food/ordering/system/customer/service/CustomerServiceApplication.java

Or use mvn clean install command to build the project and create docker images.

A sample dependency graph for easy reference:

All the above four services follows Clean architecture and Domain driven design principles. According to those patterns, all the services have arranged in similar way. Below you can see a sample dependency graph which is clearly showing above design rules.

You can clearly see that in the dependency graph most independent component is domain-core module, which contains core domain logics. This module does not depend on any other low-level modules. All the other modules are just plugins for this domain-core module.

How services are interacted with each other?

Apache Kafka is used as the message-broker to build the event-driven architecture across all services. You can find the configurations and avro models related to kafka in infrastructure/kafka directory.

Main design principles

1. Clean (Hexagonal) architecture -> Ports and adapters
2. Domain Driven Design (DDD)
3. SAGA Pattern: Process & Rollback transactions.
4. Outbox Pattern: Make the system more resilient and fault tolerance with outbox tables.
   • Prevent concurrency issues with Optimistic locks & DB Constraints.
   • Keep updating SAGA and Order Status for each operation.
5. CQRS pattern with event sourcing.

You can find further information in each service modules.