CodePlayground

*This project is part of Aalto University's Designing and Building Scalable Web Applications course (completed in spring 2024).

This project is a web application designed to assist users in practicing programming. It provides programming assignments, a code editor, and an automated grading system. Users can submit their code for evaluation and receive real-time feedback. The application is built with scalability in mind, incorporating multiple servers, load balancing, caching, and more.

Features

• Database: Stores submissions in a Postgres database and avoids regrading identical submissions.
• Message queue: Uses Redis list to manage grading requests and processes them one by one.
• Real-time communication: Users receive real-time updates on their submission status without needing to refresh the page (short polling).
• End-to-End Tests: Written with Playwright to ensure the application works as expected.
• Performance Tests: Written with k6 to measure and optimize application performance.
• User Points System: Tracks and displays user progress based on completed assignments.
• Load Balancing for Grader API: Supports multiple grader deployments to handle submissions efficiently by using NGINX.
• Caching: Implements caching mechanisms to improve performance by using Redis.
• Styling: Uses TailwindCSS for a consistent and user-friendly interface.
• Also Separate configurations for development and production environments.

Project structure

├── e2e-playwright
│   └── tests                # End-to-end tests for the application
├── flyway
│   └── sql                  # Database migration scripts
├── grader-api
│   ├── database             # Database interaction for the grader API
│   └── services             # Services related to grading
├── grader-image
│   └── example-test-code    # Example test code for the grader
├── k6                       # Performance testing scripts
├── nginx                    # Configuration for the NGINX server
├── programming-api
│   ├── controllers          # API controllers for handling requests
│   ├── database             # Database interaction for the programming API
│   ├── services             # Services related to programming assignments
│   └── util                 # Utility functions (caching and sendind to queue)
├── programming-ui           # User interface (Astro, Svelte and Tailwind)
└── redis                    # Redis configuration

Deployment and testing

**Instructions about deployment and testing the application locally are in the ./RUNNING.md file.

Reflection

See REFLECTION.md for a brief description of the application, key design decisions, and potential improvements for performance.