High Level Architecture

The system is designed with a layered approach, ensuring separation of concerns and maintainability.

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1. Client Layer

• Web Application: This is the browser-based interface for users to interact with the platform.

• Mobile Application: A mobile client for users to access the platform's functionalities on their devices.

2. API Gateway

• HTTPS/TLS: All client requests first pass through an API Gateway, which secures communication using HTTPS/TLS, providing a single entry point to the backend services.

3. Spring Boot Application (Backend)

This is the core of the application, structured into several internal layers:

Web Layer (Controllers)

• AuthController: Handles user authentication and authorization requests.

• UserController: Manages user-specific operations.

• AdminController: Provides endpoints for administrative tasks.

Security Layer

• JwtAuthenticationFilter: Intercepts requests to validate JWT tokens.

• AuthenticationManager: Manages the authentication process.

• JwtTokenProvider: Responsible for generating and validating JWT tokens.

Service Layer

• AuthService: Manages user authentication, registration, OTP verification, and token refreshing.

• KycService: Handles Know Your Customer (KYC) processes, including document submission and status updates.

• MintService: Manages minting requests for digital assets.

• UserService: Manages user profiles and whitelisted wallets.

• WalletService: Deals with user wallets.

• OtpService: Manages One-Time Password generation and verification.

Integration Layer

• EmailNotificationService: Handles sending email notifications (e.g., OTPs, KYC status changes).

• DocumentStorageService: Manages the storage of documents (e.g., KYC documents).

Repository Layer

• UserRepository, KycDocumentRepository, MintRepository, RefreshTokenRepository, OtpRepository, WalletRepository.

• These interfaces abstract the data access logic, interacting with the underlying database.

4. Azure Services (West Europe)

The application leverages several Azure cloud services for core functionalities:

• PostgreSQL Flexible Server: The primary relational database for storing all application data (users, KYC documents, mint requests, tokens, OTPs, wallets).

• Azure Blob Storage (kyc container): Used for secure and scalable storage of KYC documents.

• SMTP Server (Spring Mail): Utilized by EmailNotificationService for sending emails.

5. Configuration

• Environment Variables (App Service Settings): Critical application configurations, such as API URLs, database credentials, and JWT secrets, are managed securely through environment variables.