A simple implementation of a micro-service architecture

Inspred and ideas taken from the following articles.

• https://www.cncf.io/blog/2021/07/19/think-grpc-when-you-are-architecting-modern-microservices/
• https://microservices.io/patterns/data/database-per-service.html

Services:

• Product
• Order
• User

Typical user scenario:

• Logs in to service -> User
• View available products -> Product
• Store products in cart -> Order
• Order stored products -> Order, Product, User

This project uses gRPC & protocol buffers for data communication. Each service is intended to work as a microservice with an gateway orchestrating in front of them.

Highlight

The intention of this project was to get an understading of using grpc & protocol buffers, and implement them in a microservice architecture. The overall structure follows the API Gateway pattern, which knows which endpoint of the available microservices to call for a given request. Here's an example.

1. /order/purchase/ endpoint is called when the user wants to buy all the stored products in the user's cart
2. When the requst is made, the gateway service would first call GetCredit rpc call to the user service to get the user id and the user's current credit
3. Then it uses the user id to use the OrderInCart rpc call to get all the ids of the stored products of the users' cart
4. After that, it uses the product ids to get the aggregate sum of all the products by calling GetProduct
5. Finally, it compares the users' current credit(gotten from step 2) and the aggregate sum to determine whether the user can make the purchase

How to Run & usage scenario

• docker-compose build then up to bring up service containers
• send localhost:8080/initdb request to initialize database
• signup localhost:8080/signup/ include username and password in post request
• login localhost:8080/user/login/ same as signup, and remember the token
• see products localhost:8080/product/all/, remember product ids in order to purchase them
• add to cart localhost:8080/order/new/, include token and productIds
• purchase items in cart localhost:8080/order/purchase, include token, the resopnse will tell if you have enough credit to buy all the stored products
• a sample walkthrough can be imported by using postman's collection json file