File for your Crypto Monitor backend system. It includes:

• 📁 Project structure
• ⚙️ Setup instructions
• 🚀 How to run each service
• 🧪 Example API endpoints
• 🖼️ Space for inserting a project diagram or screenshot

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# 📈 Crypto Monitor Backend System

This is a full backend microservice system for tracking real-time cryptocurrency statistics using the CoinGecko API. It consists of two services:

- `api-server` — Exposes a REST API and stores stats in MongoDB
- `worker-server` — Background service that fetches stats and sends via NATS

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## 📁 Project Structure

```bash
crypto-monitor/
├── api-server/
│   ├── src/
│   │   ├── controllers/
│   │   │   └── statsController.js     # API logic for returning stats and deviation
│   │   ├── models/
│   │   │   └── CryptoStat.js          # Mongoose schema for stats data
│   │   ├── routes/
│   │   │   └── statsRoutes.js         # API routes (GET endpoints)
│   │   ├── services/
│   │   │   └── coingeckoService.js    # CoinGecko fetching logic (can be reused)
│   │   ├── utils/
│   │   │   └── db.js                  # MongoDB connection helper
│   │   ├── index.js                   # Main server file (starts Express + DB)
│   │   ├── nats.js                    # NATS listener for stats from worker
│   │   └── storeCryptoStats.js       # Handles writing received stats to DB
│   ├── .env                           # Environment config (PORT, MONGO_URI, NATS_URL)
│   ├── package.json                   # Dependencies and scripts
│
├── worker-server/
│   ├── src/
│   │   ├── index.js                   # Main loop to fetch and send stats
│   │   └── nats.js                    # NATS publisher setup
│   ├── .env                           # Environment config (NATS_URL)
│   ├── package.json                   # Dependencies and scripts

---

🛠️ Setup Instructions

1. Clone the Repo

git clone https://github.com/your-username/crypto-monitor.git
cd crypto-monitor

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2. Install Dependencies

Install packages for both services:

cd api-server
npm install

cd ../worker-server
node src\index.js

cd projectname
nats-server

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3. Set Up Environment Variables

Create a .env file in both api-server/ and worker-server/ folders.

🔐 For api-server/.env:

PORT=3000
MONGO_URI=mongodb://localhost:27017/crypto-monitor
COINGECKO_API=xxxxxxxxxx

🔐 For worker-server/.env:

NATS_URL=nats://localhost:4222

---

4. Start Required Services

Make sure these are running on your machine:

• 🐳 MongoDB — database

---

🚀 Running the Services

✅ Start the API Server

cd api-server
npm start

This runs Express on the port defined in .env (default: 5000).

🔁 Start the Worker Server

cd worker-server
node src\index.js

The worker will fetch stats every minute and send to the API server via NATS.

---

🧪 API Endpoints

1. Get Latest Stats

GET /api/stats/latest?coin=bitcoin

Query Params:

• coin — bitcoin, ethereum, or matic-network

Response:

{
  "price": 12345.67,
  "marketCap": 234567890,
  "24hChange": 1.23
}

---

2. Get Price Standard Deviation (Last 100 records)

GET /api/stats/deviation?coin=bitcoin

Response:

{
  "deviation": 123.45
}

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🖼️ Project Diagram / Screenshot

✅ 1. API Server Started Successfully This screenshot shows the terminal output of the api-server running successfully.

✅ 2. Worker Server Fetching Data This screenshot shows the worker-server fetching crypto stats and publishing them via NATS.

✅ 3. NATS Server Running This screenshot shows the NATS server up and running, enabling message communication between services.

📊 4. MongoDB Before Inserting Crypto Stats Initial state of the CryptoStats collection in MongoDB Compass (empty or with minimal data).

📊 5. MongoDB After 15 Minutes (Crypto Data Inserted) After 15 minutes, the worker has fetched and inserted multiple crypto stats documents (Bitcoin, Ethereum, Matic).

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🧠 Tech Stack

• Node.js (Express + NATS + Mongoose)
• MongoDB for data storage
• NATS for lightweight service communication
• CoinGecko API for real-time crypto stats

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📬 Contact

Created by Mohammed Vijahath. Contributions welcome!