Ποια είναι η μηχανική σύνδεσης του χρήστη στο σύστημα;

The login mechanics include:

1. Data entry: The user enters their identification data (e.g., login/email and password) into the form fields.
2. Request sending: The data is sent to the server via the HTTPS protocol.
3. Server-side validation: The server checks the correctness of the entered data (format, existence).
4. Authentication: The server searches for the user in the database using the entered identifiers and compares the hash of the entered password with the stored hash.
5. Authorization: If authentication is successful, the server determines the user's access rights to resources.
6. Response formation:
   • On successful login: The server generates a token (e.g., JWT, session ID) and sends it to the client (often in the response header or cookie). Additional user information may also be sent.
   • On failed login: The server sends a response with an error (e.g., "Invalid username or password").
7. Client-side response handling:
   • On success: The client stores the token (e.g., in Local Storage, Session Storage, cookie) and redirects the user to a protected page.
   • On failure: The client displays an error message to the user.

Example of a simplified request structure:

// POST /api/v1/login
{
  "username": "user@example.com",
  "password": "mysecretpassword"
}

Example of a successful response:

// 200 OK
{
  "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
  "userId": 1,
  "role": "user"
}

Example of an error response:

// 401 Unauthorized
{
  "message": "Invalid credentials"
}