MongoDB & DataStax HCD Compatibility Demo

A comprehensive web application demonstrating seamless database portability between MongoDB Atlas and DataStax HCD (Hyper Converged Database) using their compatible Data APIs.

🎯 Demo Purpose

This application showcases how applications built for MongoDB can seamlessly migrate to DataStax HCD without any code changes, demonstrating true database portability through compatible Data APIs.

✨ Features

• 🔄 Live Database Switching: Toggle between MongoDB and HCD instantly via UI toggle
• 📦 One-Click Data Migration: Sync all MongoDB records to DataStax HCD with a single click
• 👥 User Management: Create, view, and delete user profiles
• 🎨 Modern UI: Responsive Bootstrap interface with real-time database status
• 🔗 Consistent Schema: UUID-based document structure across both databases
• ⚡ Real-time Operations: Instant CRUD operations with confirmation dialogs
• 📊 Database Monitoring: Visual indicators showing active database type
• 🚀 Zero Downtime Switching: Change databases without restarting the application

🏗️ Architecture

┌─────────────────┐    ┌──────────────────┐    ┌─────────────────┐
│   Web Interface │────│  Database Layer  │────│   MongoDB OR    │
│   (Flask + UI)  │    │   (Abstraction)  │    │   DataStax HCD  │
└─────────────────┘    └──────────────────┘    └─────────────────┘

🚀 Quick Start

Prerequisites

• Python 3.10+
• MongoDB Atlas account OR DataStax HCD instance
• Git

1. Clone Repository

git clone https://github.com/shiragannavar/MongoDB-DataStax-Compatibility-Demo.git
cd MongoDB-DataStax-Compatibility-Demo

2. Setup Virtual Environment

python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate
pip install -r requirements.txt

3. Configure Database

Copy .env.example to .env and configure your database:

cp .env.example .env

For MongoDB Atlas:

DATABASE_TYPE=mongodb
MONGODB_URI=mongodb+srv://<username>:<password>@<cluster>.mongodb.net/?retryWrites=true&w=majority
MONGODB_DATABASE=user_profiles

For DataStax HCD:

DATABASE_TYPE=hcd
HCD_API_ENDPOINT=http://<your-hcd-endpoint>:8181
HCD_USERNAME=<your_username>
HCD_PASSWORD=<your_password>
HCD_KEYSPACE=default_keyspace

4. Run Application

python app.py

Visit http://localhost:5001 to see the application in action!

🔄 Live Database Switching Demo

Real-time Database Toggle

1. Visit the application at http://localhost:5001
2. Locate the toggle switch in the Database Status card
3. Toggle left (unchecked): MongoDB (green badge)
4. Toggle right (checked): DataStax HCD (yellow badge)
5. Watch the magic: Instant database switching without restart!

📦 One-Click Data Migration

MongoDB to DataStax HCD Sync

When MongoDB is active, you'll see a "Sync to DataStax HCD" button:

1. Ensure MongoDB is active (toggle switch left/unchecked)
2. Click "Sync to DataStax HCD" button in the user list header
3. Watch the sync process: Button shows spinner with "Syncing..." text
4. Success notification: "Successfully synced X users to DataStax HCD"
5. Switch to DataStax HCD: Toggle right to verify all data copied

Migration Features

• Zero Transformation: Records copied exactly as-is from MongoDB
• Duplicate Handling: Skips existing records gracefully
• Progress Feedback: Loading states and success/error notifications
• Bulk Operation: Migrates all users in a single operation
• Error Resilience: Continues sync even if individual records fail

Traditional Configuration Method

Alternatively, you can still switch databases via configuration:

1. Update .env: Change DATABASE_TYPE=mongodb or DATABASE_TYPE=hcd
2. Restart the application
3. Verify the database badge updates accordingly

Verify Compatibility

• Live switching: Toggle between databases in real-time
• Same interface: Identical functionality regardless of database
• Consistent data: UUID-based schema works across both databases
• Zero code changes: Same application logic for both databases
• Data migration: One-click sync from MongoDB to DataStax HCD

📋 API Reference

Endpoint	Method	Description
/	GET	Main dashboard with user list
/create_user	GET/POST	User creation form and handler
/delete_user/<id>	POST	Delete user by UUID
/api/users	GET	JSON API - Get all users
/api/db_info	GET	Current database connection info
/api/switch_database	POST	Switch between MongoDB and HCD
/api/sync_to_hcd	POST	Migrate all MongoDB records to DataStax HCD

🏗️ Project Structure

├── app.py                 # Flask web application
├── database.py            # Database abstraction layer
├── insert_sample_data.py  # Script to generate 25 sample records
├── requirements.txt       # Python dependencies
├── .env.example          # Environment template
├── README.md             # This file
├── templates/            # Jinja2 HTML templates
│   ├── base.html        # Base layout
│   ├── index.html       # User dashboard
│   └── create_user.html # User creation form
└── static/              # Frontend assets
    ├── css/style.css    # Custom styles with VI branding
    └── js/main.js       # JavaScript functionality

🔧 Technical Implementation

Database Abstraction Layer

The DatabaseManager class in database.py provides a unified interface:

class DatabaseManager:
    def __init__(self):
        self.db_type = os.getenv('DATABASE_TYPE', 'mongodb')
        self._setup_connection()
    
    def create_user(self, user_data):
        # Works with both MongoDB and HCD
    
    def get_all_users(self):
        # Consistent across databases
    
    def delete_user(self, user_id):
        # Same logic, different clients
    
    def sync_mongodb_to_hcd(self):
        # One-click migration from MongoDB to DataStax HCD

Data Migration Implementation

The sync functionality demonstrates true database portability:

def sync_mongodb_to_hcd(self):
    # Get all MongoDB records
    mongodb_users = list(self.collection.find({}))
    
    # Setup temporary HCD connection
    hcd_manager = DatabaseManager()
    hcd_manager.db_type = 'hcd'
    hcd_manager._setup_hcd()
    
    # Insert records without transformation
    for user in mongodb_users:
        hcd_manager.collection.insert_one(user)

Consistent Schema

Both databases use identical document structure:

{
  "_id": "550e8400-e29b-41d4-a716-446655440000",
  "name": "John Doe",
  "email": "[email protected]",
  "age": 30,
  "city": "New York",
  "created_at": "2025-09-03T08:35:00.000Z"
}

🎯 Key Demo Points

1. Live Database Switching: Toggle between databases without restarting
2. One-Click Data Migration: Sync all MongoDB records to DataStax HCD instantly
3. Zero Code Changes: Same application logic works with both databases
4. Visual Confirmation: UI clearly shows which database is active
5. Identical Functionality: All features work exactly the same way
6. Schema Consistency: UUID-based documents ensure portability
7. Production Ready: Error handling, validation, and modern UI
8. Sample Data: 25 realistic user records for comprehensive testing

🛠️ Technologies Used

• Backend: Python 3.10, Flask 2.3
• Database Clients: PyMongo (MongoDB), AstraPy (HCD)
• Frontend: Bootstrap 5, JavaScript ES6
• Database: MongoDB Atlas, DataStax HCD
• Deployment: Environment-based configuration

📝 Environment Variables

Variable	Description	Example
DATABASE_TYPE	Database type (mongodb or hcd)	mongodb
MONGODB_URI	MongoDB connection string	mongodb+srv://<username>:<password>@<cluster>.mongodb.net/
MONGODB_DATABASE	MongoDB database name	user_profiles
HCD_API_ENDPOINT	HCD Data API endpoint	http://localhost:8181
HCD_USERNAME	HCD username	<your_username>
HCD_PASSWORD	HCD password	<your_password>
HCD_KEYSPACE	HCD keyspace name	default_keyspace

🤝 Contributing

1. Fork the repository
2. Create a feature branch: git checkout -b feature-name
3. Commit changes: git commit -am 'Add feature'
4. Push to branch: git push origin feature-name
5. Submit a Pull Request

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🔗 Related Links

• MongoDB Atlas
• DataStax HCD Documentation
• [Data API Comparison Guide](https://docs.datastax.com/en/astra-db-se---

Built with ❤️ to demonstrate the power of database portability