eCommerce Application

eCommerce application is used for the didactic purpose only. It is a support project for Ionut Balosin's training.

Please visit the author's website for more details.

For the full copyright and license information, please view the LICENSE file that was distributed with this source code.

High-level description

The purpose of this application is to have a platform where customers can find products, shop around using a cart, check out the products and initiate payments.

The provided services are:

Product service - handles the product catalog and exposes an API to create, retrieve, update, and delete products. It comes with a prefilled product catalog.
Shopping cart service - handles the user's shopping cart and exposes an API to create, retrieve, update, delete and check out the user's shopping cart items.
Order service - handles the user's orders and exposes an API to retrieve the historical orders and update them
Payment service - handles the orders' payments using an external system

Software architecture diagram

Among the architectural styles, design tactics, and patterns demonstrated in this project:

Event-driven microservices architecture
API-driven development approach
Schema-first development approach
Shared-nothing database approach
Schema registry
REST architectural style (e.g., RESTful APIs)
Scalability (e.g., horizontal scalability)
Location decoupling
Resiliency
Caching (e.g., local/embedded)
Asynchronous logging
Change data capture design pattern
Listen to yourself design pattern
Data transfer object enterprise application pattern

Among the technologies, frameworks, and libraries included in this project:

Spring Boot
JdbcTemplate (e.g., query, update, batch update)
Caffeine caching
Kafka
PostgreSQL
Flywaydb
Debezium
Testcontainers
Resilience4j (e.g., circuit breaker, bulkhead)
Traefik (i.e., HTTP reverse proxy and load balancer)
AVRO and JSON data format
OpenAPI specification
Logback
Spotless code formatter
Docker compose

Set-up

Please make sure you have properly installed (and configured):

JDK 17 (i.e., latest LTS)
Docker
cURL
Postman

Compile, run tests, and package

./mvnw spotless:apply package

Note The argument spotless:apply is optional but nice to have it

Bootstrap all the services (and the dependencies) with Docker

./bootstrap.sh

To check if all Docker containers are up and running execute the below command:

docker ps -a

Important: On Windows using Docker compose v2 there is a known limitation while horizontally scaling a service by using port ranges like "8080-8081:80".

At the moment, the workaround is to simply copy-paste (multiple times) the same service inside the Docker compose YAML file and explicitly assign different ports to each.

Register the PostgreSQL connector

The PostgreSQL connector is used to monitor and record the row-level changes in the PostgreSQL database schema.

Note: please make sure all services (e.g., PostgreSQL and Kafka) are up and running before registering the connector

./debezium-register-postgres.sh

Services overview via UI

Open a browser and navigate to http://localhost:26060 to access the Traefik UI (it shows endpoints, routes, services, etc.).

Open a browser and navigate to http://localhost:19000 to access the Kafdrop UI (it shows topics, partitions, consumers, messages, etc.).

Open a browser and navigate to http://localhost:18080 to access the Debezium UI (it shows the PostgreSQL connector).

Note: these ports are configured in Docker compose YAML files.

Local tests with Postman

open Postman
import the provided API collections, corresponding to each project, as follows:
- ./ecommerce-app/order-service/postman
- ./ecommerce-app/product-service/postman
- ./ecommerce-app/shopping-cart-service/postman
to simulate a basic test scenario please trigger the below requests (in this sequence):

GET http://localhost:{{port}}/products

POST http://localhost:{{port}}/cart/{{userId}}/items

POST http://localhost:{{port}}/cart/{{userId}}/checkout

GET http://localhost:{{port}}/orders/{{userId}}/history

Note: the ports (i.e., service port or Traefik load balancer port) are already configured as variables in the Postman collections

TODOs

A few TODO items might be:

implement a user service (to handle user identities)
implement a notification service (to handle all kinds of notifications)
implement APIs pagination
implement database bulk updates for the remaining APIs
minimize the object creation in (DTO/entity) mappers

musanabiyev / ecommerce-app