OBSYS: Operating System Simulation Framework

OBSYS is an advanced Operating System Simulation Framework designed to simulate, visualize, and analyze CPU scheduling algorithms in real-time. It provides a highly decoupled Client-Server architecture with a live interactive web dashboard and a seamless Command-Line Interface (CLI).

Key Features

• Real-Time Visualization: Live Gantt Chart and Process Visualizer dynamically updating execution states based on a simulated clock.
• Multiple Scheduling Algorithms: Supports First-Come-First-Served (FCFS), Shortest Job First (SJF), Round Robin (RR), and Priority scheduling algorithms.
• Algorithm Comparison: Parallel execution and visual comparison of performance metrics (Average Waiting Time, Turnaround Time, CPU Utilization).
• Persistent State: Real-time data sync between the Terminal (CLI) and Web Dashboard via SQLite and SQLAlchemy.
• Robust Architecture: Powered by a high-performance asynchronous FastAPI backend and an interactive React + TypeScript frontend.

System Architecture

OBSYS is built on a decoupled, three-tier architecture:

1. Backend (Python / FastAPI / Uvicorn): The core engine handling mathematical derivations, process scheduling, and metric computations.
2. Persistence Layer (SQLite / SQLAlchemy): A data store preserving process configurations and historical simulations for comparative analysis.
3. Frontend (React / TypeScript / Vite): The user interface providing an interactive experience, leveraging custom React Hooks (useSimulation) to animate the execution history.

 Terminal (CLI) <---> Database (SQLite) <---> Backend (FastAPI) <---> Web GUI (React)

Getting Started

Prerequisites

• Python 3.8+
• Node.js & npm (for the frontend)

Installation

1. Clone the repository:

   git clone <repository_url>
   cd spd

2. Set up the backend:

   python -m venv venv
   source venv/bin/activate  # On Windows: venv\Scripts\activate
   pip install fastapi uvicorn sqlalchemy pydantic

3. Set up the frontend:

   cd frontend
   npm install

Running the Application

Using the OBSYS CLI (Recommended) OBSYS provides a built-in CLI for seamless orchestration. From the root directory:

./obsys schedule

This command automatically spins up both the FastAPI backend server and the React frontend server in the background.

Running Manually

• Backend: cd backend && uvicorn api:app --reload
• Frontend: cd frontend && npm run dev

Navigate to http://localhost:5173 in your browser to interact with the visual dashboard.

Supported Scheduling Algorithms

• FCFS (First-Come-First-Served): A non-preemptive, simple queue-based execution.
• SJF (Shortest Job First): A non-preemptive algorithm that selects the process with the smallest burst time. (Proven optimal for minimal Average Waiting Time).
• Round Robin: A preemptive algorithm implementing time-slicing (Time Quantum).
• Priority Scheduling: Determines process execution order based on priority values (lower value = higher priority).

Analytics and Metrics

The framework automatically calculates and compares critical performance metrics:

• Average Waiting Time (AWT): Turnaround Time - Burst Time.
• Average Turnaround Time (ATAT): Finish Time - Arrival Time.
• CPU Utilization: Evaluating system efficiency based on total burst time over total system time.

Security & Best Practices

• CORS Configuration: Strictly isolates frontend-backend communication.
• Input Validation (Pydantic): Protects the API from invalid or mathematically impossible simulation values.
• Targeted SQL Injection Prevention: SQLAlchemy ORM parametrizes all queries securely.

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Created as part of an OS System Architecture Simulation Project.