N-Tier Architecture

N-Tier Architecture is a software architecture pattern that separates an application into multiple logical layers or tiers. Each tier is responsible for specific functions, promoting separation of concerns and scalability.

• **Separation of Concerns**: Each tier has a distinct responsibility.
• **Scalability**: Tiers can be scaled independently based on demand.
• **Maintainability**: Changes to one tier have minimal impact on others.
• **Reusability**: Tiers can be reused across different applications.

The N-Tier architecture typically consists of the following layers:

1. **Presentation Layer**: User interface and user experience management.
2. **Business Logic Layer**: Implements the core functionality of the application.
3. **Data Access Layer**: Manages data persistence and retrieval.
4. **Database Layer**: Physical storage of data.

The diagram below illustrates the typical flow of data in an N-Tier architecture:

graph TD;
    A[User Interface] --> B[Business Logic Layer];
    B --> C[Data Access Layer];
    C --> D[Database Layer];
            

• **Use well-defined APIs** for communication between layers.
• **Implement caching** to enhance performance.
• **Maintain loose coupling** between layers to improve flexibility.
• **Adopt a security model** for data access and transmission.

Below is a simple code example demonstrating the separation of layers in a Node.js application:

const express = require('express');
const app = express();
const bodyParser = require('body-parser');
const userController = require('./controllers/userController');

app.use(bodyParser.json());

app.get('/users', userController.getAllUsers);
app.post('/users', userController.createUser);

app.listen(3000, () => {
    console.log('Server running on port 3000');
});