KoshFlow - Cloud-Native Banking Microservices Platform

Overview

KoshFlow is a modular, production-grade banking application built with Java, Spring Boot, and Docker. It implements core banking features, leverages event-driven architecture with Kafka and RabbitMQ, and provides robust notification and search capabilities. The system is designed for scalability, extensibility, and future AI integration.

Architecture

• Microservices: Each business domain (accounts, users, transactions, notifications, authentication, search) is a separate Spring Boot service.
• API Gateway: Central entry point for all APIs, with JWT-based authentication and routing.
• Service Discovery: Eureka registry for dynamic service registration and discovery.
• Messaging: Kafka and RabbitMQ for asynchronous, decoupled communication.
• Persistence: PostgreSQL for relational data, Elasticsearch for search/analytics.
• Containerized: All services and dependencies are orchestrated via Docker Compose.

Service Architecture Diagram

graph TB
    %% Client and Gateway Layer
    Client[🖥️ Frontend/Client Application]
    Gateway[🌐 API Gateway<br/>Port: 9080]
    
    %% Authentication
    Auth[🔐 Auth Service<br/>JWT Authentication<br/>Port: 8085]
    
    %% Service Discovery
    Eureka[📋 Eureka Server<br/>Service Registry<br/>Port: 8761]
    
    %% Core Services
    User[👤 User Service<br/>Profile Management<br/>Port: 8080]
    Account[💰 Account Service<br/>Balance Management<br/>Port: 8081]
    Trans[💳 Transaction Service<br/>Money Transfers<br/>Port: 8082]
    
    %% Support Services
    Notif[📧 Notification Service<br/>Email & Alerts<br/>Port: 8083]
    ES[🔍 Elasticsearch Service<br/>Search & Analytics<br/>Port: 8084]
    
    %% Message Brokers
    Kafka[(📨 Apache Kafka<br/>Event Streaming)]
    RabbitMQ[(🐰 RabbitMQ<br/>Message Queue)]
    
    %% Client Flow
    Client -->|HTTPS Requests| Gateway
    Gateway -->|Validate Token| Auth
    Gateway -->|Route Requests| User
    Gateway -->|Route Requests| Trans
    Gateway -->|Route Requests| Account
    
    %% Service Discovery (Registration)
    Auth -.->|Register & Discover| Eureka
    User -.->|Register & Discover| Eureka
    Trans -.->|Register & Discover| Eureka
    Account -.->|Register & Discover| Eureka
    Notif -.->|Register & Discover| Eureka
    ES -.->|Register & Discover| Eureka
    Gateway -.->|Register & Discover| Eureka
    
    %% Inter-Service Communication via Kafka
    Trans -->|Transaction Events| Kafka
    Kafka -->|Account Updates| Account
    Account -->|Balance Events| Kafka
    Kafka -->|Transaction Status| Trans
    Kafka -->|User Events| User
    Kafka -->|Search Index| ES
    
    %% RabbitMQ for Notifications
    User -->|Notification Messages| RabbitMQ
    RabbitMQ -->|Send Notifications| Notif
    
    %% Styling
    classDef clientStyle fill:#e1f5fe,stroke:#01579b,stroke-width:2px,color:#000
    classDef gatewayStyle fill:#f3e5f5,stroke:#4a148c,stroke-width:2px,color:#000
    classDef serviceStyle fill:#e8f5e8,stroke:#2e7d32,stroke-width:2px,color:#000
    classDef authStyle fill:#fff3e0,stroke:#e65100,stroke-width:2px,color:#000
    classDef discoveryStyle fill:#fce4ec,stroke:#880e4f,stroke-width:2px,color:#000
    classDef messageStyle fill:#f1f8e9,stroke:#33691e,stroke-width:2px,color:#000
    
    class Client clientStyle
    class Gateway gatewayStyle
    class User,Account,Trans,Notif,ES serviceStyle
    class Auth authStyle
    class Eureka discoveryStyle
    class Kafka,RabbitMQ messageStyle

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Services

Service	Description	Port	Link to README
user-service	Manages user profiles	8080	user-service
account-service	Manages user accounts and balances	8081	account-service
transaction-service	Handles money transfers and history	8082	transaction-service
notification-service	Sends notifications (email, etc.)	8083	notification-service
elasticsearch-service	Search/analytics for transactions	8084	elasticsearch-service
auth-service	Handles authentication (JWT)	8085	auth-service
registry-service	Eureka service registry	8761	registry-service
gateway-service	API Gateway, routing, JWT validation	9080	gateway-service

Sample Business Flow: Transaction Processing

1. Initiate Transaction:

   • A user initiates a transaction via the transaction-service API.
   • The transaction is validated, saved to the database, and published to Kafka.

2. Account Processing:

   • The account-service consumes the Kafka event, processes the transaction (e.g., balance updates), and publishes the result back to Kafka.

3. Transaction Completion:

   • The transaction-service listens for the completion event, updates the transaction status, and publishes it to Elasticsearch for indexing.

4. User Notification:

   • The user-service listens for the completion event, gathers user details, and sends a message to RabbitMQ.
   • The notification-service consumes the RabbitMQ message and sends an email to the user.

Quick Start (Docker Compose)

1. Clone the repository.
2. Ensure Docker and Docker Compose are installed.
3. Run: docker-compose up --build
4. Access services via their respective ports (see table above).

Prerequisites

• Java 21+
• Maven 3.8+
• Docker & Docker Compose

Configuration

• Each service has its own application.properties for environment-specific settings.
• Common environment variables:
  • Database: spring.datasource.*
  • Kafka: spring.kafka.bootstrap-servers
  • RabbitMQ: spring.rabbitmq.*
  • Eureka: eureka.client.service-url.defaultZone
  • JWT Secret (auth-service): jwt.secret

Monitoring & Health

• Spring Boot Actuator endpoints are enabled for all services.
• Eureka dashboard available at http://localhost:8761.

Contributing

1. Fork the repo and create a feature branch.
2. Make changes and add tests.
3. Submit a pull request.

License

MIT

Contact

For questions or support, contact: mslalith17@gmail.com