DEMO Microservices-Based Billing Management System

This project demonstrates a microservices-based architecture built with Spring Boot, Spring Cloud, and Spring Data JPA. It manages customers, products, and billing services, and uses Spring Cloud Gateway for routing and Eureka Discovery Server for service registration and discovery.

Architecture Overview

The system is based on a set of microservices that communicate with each other to manage customer data, product inventories, and bills. These microservices are registered with Eureka Discovery Server and accessed through Spring Cloud Gateway.

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Project Structure

This project consists of the following services:

• discovery-service: Eureka Discovery Server
• gateway: Spring Cloud Gateway
• customer-service: Manages customer data
• inventory-service: Manages product inventory
• billing-service: Handles billing operations

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├── billing-service (Java)
├── customer-service (Java)
├── discovery-service (Java)
├── inventory-service (Java)
├── gateway (Java)
└── frontend-service (Angular)

Services

1. Customer Service

• This service is responsible for managing customer data. It provides endpoints to create, retrieve, update, and delete customers.
• Port: 8081 Screenshot of Customer API Response:

Screenshot of Customer UI:

2. Inventory Service

• The Inventory Service handles all product-related operations. It provides endpoints to manage the inventory of products including creating, updating, and retrieving product information.
• Port: 8082

Screenshot of Inventory API Response:

Screenshot of Product UI:

3. Billing Service

• The Billing Service manages billing operations, which include generating bills for customers based on the products they purchase. It integrates with the Customer Service and Inventory Service using Feign Clients for retrieving customer and product data.
• Port: 8083
• Technology: Spring Boot, Feign Clients, Spring Data JPA

4. Spring Cloud Gateway

• The Spring Cloud Gateway acts as the unified entry point for client requests. It routes requests to the appropriate services (Customer, Inventory, Billing) based on the service discovery information from Eureka.
• Port: 8888
• Technology: Spring Cloud Gateway

Example of a request through the gateway:

http://localhost:8888/CUSTOMER-SERVICE/customers
http://localhost:8888/INVENTORY-SERVICE/products

Screenshot of Gateway API:

5. Eureka Discovery Server

• The Eureka Discovery Server registers all the services, making it easier for them to discover and communicate with each other.
• Port: 8761
• Technology: Spring Cloud Eureka

Screenshot of Eureka Dashboard:

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Project Structure

This project consists of the following services:

• discovery-service: Eureka Discovery Server
• gateway: Spring Cloud Gateway
• customer-service: Manages customer data
• inventory-service: Manages product inventory
• billing-service: Handles billing operations

Dependencies

Here is a list of key dependencies used in each service:

Common Dependencies

• Spring Boot (v3.3.4)
• Spring Data JPA
• H2 Database (In-memory database for development)
• Lombok (for reducing boilerplate code)
• Spring Boot DevTools (for live reload during development)

Customer, Inventory, and Billing Services

• Spring Boot Starter Web: For building web and RESTful services.
• Spring Data REST: For easy exposure of repositories as RESTful endpoints.
• Spring Data JPA: For data persistence and interaction with the H2 database.

Billing Service Specific

• OpenFeign: Declarative REST client used for inter-service communication.
• Feign Clients: To communicate with Customer and Inventory services.

Gateway Service

• Spring Cloud Gateway: For routing requests to the relevant microservices.

Discovery Service

• Spring Cloud Netflix Eureka: For service discovery and registration.

Other Dependencies

• Spring Boot Actuator: Provides endpoints to monitor and manage your application.
• Spring HATEOAS: To include hypermedia links in the response data.

How to Run the Project

1. Start the Eureka Discovery Service:
   Run the discovery-service.

2. Start the Gateway Service:
   Run the gateway service.

3. Start the Customer, Inventory, and Billing Services:
   Run customer-service, inventory-service, and billing-service.

4. Access Services via Gateway:

• Customer Service: http://localhost:8888/CUSTOMER-SERVICE/customers
• Inventory Service: http://localhost:8888/INVENTORY-SERVICE/products
• Billing Service: http://localhost:8888/BILLING-SERVICE/bills

5. Access Eureka Dashboard:
   • Eureka dashboard will be available at http://localhost:8761/
   • Eureka dashboard will be available at http://localhost:8761/