eUNI Backend Documentation

Overview

The backend of the eUNI application is responsible for secure data management, business logic processing, and API service delivery for a student scheduling web platform. It is implemented in C# using ASP.NET Core 8 and follows a multi-layered N-Layer architecture.

Backend Architecture

The backend is divided into three core layers (N-Layered Architecture):

• User Interface Layer - contains controllers that expose REST API endpoints. Responsible for receiving HTTP requests and returning responses.
• Business Logic Layer (BLL) - contains services that handle business rules and data processing. Acts as an intermediary between UI and data access layers.
• Data Access Layer (DAL) - uses Entity Framework Core (EF Core) for ORM. Handles CRUD operations and database interactions.

Folder Structure (Backend)

• eUNI-API/
  • Attributes/ – Custom attributes (e.g., role-based auth)
  • Configuration/ – JWT and other config settings
  • Controllers/ – API endpoints
  • Data/ – EF Core DB context and migrations
  • Enums/ – Constant definitions
  • Exception/ – Custom exceptions
  • Helpers/ – Shared utility methods
  • Middlewares/ – Global error handling logic
  • Models/DTOs & Models/Entities – Data transfer and DB models
  • Repositories/ – Data layer access logic
  • Services/ – Business logic implementations
  • Program.cs – Entry point and API bootstrapping
  • appsettings.json – Environment-based configurations

Security

Authentication & Authorization

Tokens are transmitted via HTTP headers and cookies to ensure secure session management. The application uses:

• JWT (JSON Web Token) - for stateless authentication.
• Refresh Token - stored in HTTP-only cookies, used to renew JWTs.

The default expiration time for tokens is:

• JWT: 15 minutes
• Refresh Token: 3 days

Password Handling

Passwords are hashed using bcrypt with added salt on frontend. Next the server-side app uses hashing utilizes PBKDF2 to mitigate brute-force attacks.

Database (PostgreSQL)

User Entities

• Users: Stores credentials, role, and hashed passwords
• Roles: Role-based access control
• RefreshTokens: Stores refresh tokens for session extension
• PasswordResetLogs: For password recovery

Academic Structure

• Classes, ClassDates, Hours - Handle scheduling
• FieldOfStudy, FieldOfStudyLogs - Degree programs
• StudentGroups, Groups - Student cohorts
• OrganizationOfTheYear, DaysOff, Years - Academic calendar

API Design

The backend supports role-based access via JWT claims. RESTful APIs provide endpoints for:

• User registration & login
• Profile & schedule management
• Admin features: course/year management, user roles

External Integration

Ical.Net library is used to generate iCalendar-compatible files. Schedule exports to Google Calendar or Outlook are supported.

Error Handling

A global middleware component captures unhandled exceptions and returns standardized JSON responses with the appropriate HTTP status codes (e.g., 400, 403, 500). To support this mechanism, custom exception classes were implemented to handle specific error types, including:

• HttpBadRequestException
• HttpUnauthorizedException
• HttpForbiddenException
• HttpNotFoundException
• HttpCustomException

Configuration

1. Copy .env.example to .env.

cp .env.example .env

2. Create a secure key for the JWT__Key environment variable using the following command.

node -e "console.log(require('crypto').randomBytes(256).toString('hex'));"

3. Configure CORS by specifing the frontend adress in AllowedOrigins.

Development

When ASPNETCORE_ENVIRONMENT is set to Development in the .env file, the Swagger UI is available at http://localhost:5000/swagger

Demo version

A live demo of the app is hosted at: api-euni.jakubniewelt.pl

NOTE: Deployment handled via Coolify with GitHub Actions integration for automated CI/CD.