# System Architecture --- **Document Version:** 1.0 **Project:** Student Bazaar **Document Type:** System Architecture Specification **Status:** Approved **Last Updated:** 28 June 2026 **Author:** Nemmi Tangha --- # 1. Purpose This document describes the overall architecture of Student Bazaar, including the application's structure, major components, communication flow, architectural patterns, and design principles. The objective is to ensure that the application remains scalable, maintainable, secure, and easy to extend throughout its lifecycle. --- # 2. Architecture Overview Student Bazaar follows a **Layered, Feature-Based Modular Architecture** built using the Python Flask framework. The application separates responsibilities into independent modules while organizing business logic into dedicated service layers. This architecture promotes: * High maintainability * Low coupling * High cohesion * Code reusability * Easier testing * Future scalability --- # 3. Technology Stack ## Backend * Python * Flask * Flask Blueprints * Flask-SQLAlchemy * Flask-WTF * Flask-Mail * Flask-Login ## Database * MySQL ## Frontend * HTML5 * CSS3 * Bootstrap 5 * JavaScript ## Development Tools * VS Code * Git * GitHub * MySQL Workbench --- # 4. Architectural Pattern Student Bazaar combines three architectural concepts: ## Layered Architecture Presentation Layer ↓ Business Logic Layer ↓ Data Access Layer ↓ Database --- ## Feature-Based Modular Design Each feature is implemented as an independent Flask Blueprint. Examples include: * Authentication * Marketplace * Chat * Offers * Meet-up * Notifications * Premium * Reports * Seller Dashboard * Administration --- ## Service Layer Pattern Business logic is separated from routes. Routes should only: * Receive requests * Validate basic input * Call services * Return responses Business rules belong inside service classes. --- # 5. Application Layers ## Presentation Layer Responsible for: * HTML Templates * Bootstrap UI * Forms * User Interaction --- ## Routing Layer Implemented using Flask Blueprints. Responsibilities include: * URL Mapping * Authentication Checks * Input Validation * Calling Services * Returning Responses Routes must remain lightweight. --- ## Service Layer Responsible for: * Business Logic * Validation * Marketplace Rules * Chat Rules * Offer Processing * Meet-up Scheduling * Notifications * Premium Validation Most application logic resides here. --- ## Data Layer Responsible for: * SQLAlchemy Models * Database Relationships * Data Persistence Models represent database entities only. --- ## Database Layer MySQL stores all persistent application data. --- # 6. Feature Modules The application is divided into the following modules. ## Authentication Responsibilities: * Registration * Login * Email Verification * Password Reset --- ## Marketplace Responsibilities: * Product Listings * Product Images * Categories * Search * Filters * Product Status --- ## Offers Responsibilities: * Price Negotiation * Counter Offers * Offer Acceptance * Offer History --- ## Chat Responsibilities: * Conversations * Message Limits * Rewarded Advertisement Unlock * Premium Chat Access --- ## Meet-up Responsibilities: * Scheduling * Updates * Acceptance * Notifications --- ## Notifications Responsibilities: * Event Notifications * System Notifications * Marketplace Alerts --- ## Seller Dashboard Responsibilities: * Listing Management * Seller Statistics * Product Analytics --- ## Reports Responsibilities: * Listing Reports * User Reports * Moderation --- ## Advertisements Responsibilities: * Banner Advertisements * Rewarded Advertisements * Advertisement Management --- ## Premium Responsibilities: * Subscription Management * Premium Validation * Premium Benefits --- ## Administration Responsibilities: * User Management * Report Review * Listing Moderation * Analytics * Advertisement Management --- # 7. Request Lifecycle Every request follows the same processing flow. Browser ↓ Flask Blueprint ↓ Service Layer ↓ SQLAlchemy Model ↓ MySQL Database ↓ Service Layer ↓ Blueprint ↓ Response This structure keeps responsibilities separated. --- # 8. Security Architecture Security is implemented across all layers. Measures include: * Password Hashing * Email Verification * CSRF Protection * SQL Injection Prevention * XSS Protection * Secure Sessions * Input Validation * Authorization Checks --- # 9. Data Flow Example: Student creates listing ↓ Marketplace Blueprint ↓ Listing Service ↓ Listing Model ↓ Database ↓ Notification Service ↓ Notification Model ↓ Database ↓ Response returned --- # 10. Scalability The architecture supports future expansion by allowing new modules to be added independently. Examples: * AI Recommendation Module * Payment Module * Mobile API * QR Verification * Push Notifications Existing modules require minimal modification. --- # 11. Error Handling Strategy Errors should be handled centrally. Categories include: * Validation Errors * Authentication Errors * Authorization Errors * Database Errors * File Upload Errors * System Errors User-friendly messages should be displayed while detailed errors are logged internally. --- # 12. Logging Strategy The application should log: * Authentication Events * Errors * Reports * Premium Purchases * Advertisement Views * Administrative Actions Logs assist with debugging, monitoring, and auditing. --- # 13. Performance Considerations The architecture is designed to support: * Database Indexing * Efficient Queries * Lazy Loading (where appropriate) * Pagination * Optimized Image Storage * Responsive User Interface --- # 14. Future Evolution The modular architecture allows additional functionality without major restructuring. Future modules may include: * AI Product Recommendations * Mobile Applications * Payment Integration * QR Verification * Push Notifications * College Verification --- # 15. Conclusion The Student Bazaar architecture follows modern software engineering principles by combining Flask Blueprints, feature-based modularization, and a service layer architecture. This design provides a clean separation of concerns, improves maintainability, supports future scalability, and establishes a solid foundation for a production-quality marketplace application.