This is a simple demonstration of a RESTful API built using the router-controller-service pattern. The API consists of endpoints for managing users and groups.

The router-controller-service pattern is a software design pattern commonly used in web applications to achieve separation of concerns and improve code maintainability. In this pattern, the application logic is divided into three layers:

• Router: Defines API endpoints and routes incoming requests to the appropriate controller.
• Controller: Handles incoming requests, interacts with the service layer to perform business logic, and sends back responses to the client.
• Service: Contains the business logic of the application, performs CRUD operations on the data, and interacts with the database or external services.

The API is structured into the following components:

• Routes: Defines API endpoints and routes requests to corresponding controllers.
• Controllers: Handles requests from the routes, invokes appropriate service methods, and sends back responses.
• Services: Contains the business logic for manipulating data and interacts with the database.

1. Install dependencies: npm i

2. Start the server: npm start

3. The API will be accessible at http://localhost:3000.

• Users:

• GET /users: Get all users

• GET /users/:id: Get a specific user by ID

• POST /users: Insert a new user

• Groups:

• GET /groups: Get all groups

• GET /groups/:id: Get a specific group by ID

• POST /groups: Insert a new group

To test the API endpoints, you can use tools like Postman or cURL. Here's an example of how to test the /users endpoint:

1. Open Postman.
2. Set the request type to POST.
3. Enter the URL http://localhost:3000/users.
4. Add the required request body parameters (if any).
5. Click on the Send button to make the request.
6. You will receive a response indicating the success or failure of the request.

You can test other endpoints by changing the request type and URL accordingly.

• Express.js: Backend framework for handling HTTP requests and routing.