CODESAMPLE
N-tier - PHP
The N-tier pattern organizes an application into distinct layers, each with a specific responsibility. This promotes separation of concerns, making the application more maintainable, testable, and scalable. A typical N-tier architecture includes a presentation tier (UI), a business logic tier, and a data access tier.
This PHP example demonstrates a simple 3-tier architecture for managing user data. The UserController (Presentation) handles requests and responses. The UserService (Business Logic) contains the core application logic for user operations. The UserRepository (Data Access) interacts with a hypothetical database (represented here by a simple array) to retrieve and store user data. This structure is common in PHP applications, particularly those using frameworks like Laravel or Symfony, and leverages PHP’s class-based structure for clear organization.
<?php
// Model: User.php
class User {
public int $id;
public string $name;
public string $email;
public function __construct(int $id, string $name, string $email) {
$this->id = $id;
$this->name = $name;
$this->email = $email;
}
}
// Data Access Layer: UserRepository.php
class UserRepository {
private array $users = [
1 => new User(1, 'John Doe', 'john.doe@example.com'),
2 => new User(2, 'Jane Smith', 'jane.smith@example.com'),
];
public function getUser(int $id): ?User {
return $this->users[$id] ?? null;
}
}
// Business Logic Layer: UserService.php
class UserService {
private UserRepository $userRepository;
public function __construct(UserRepository $userRepository) {
$this->userRepository = $userRepository;
}
public function getUserDetails(int $id): ?User {
return $this->userRepository->getUser($id);
}
}
// Presentation Layer: UserController.php
class UserController {
private UserService $userService;
public function __construct(UserService $userService) {
$this->userService = $userService;
}
public function showUser(int $id): ?string {
$user = $this->userService->getUserDetails($id);
if ($user) {
return "User ID: {$user->id}, Name: {$user->name}, Email: {$user->email}";
} else {
return "User not found.";
}
}
}
// Example Usage
$userRepository = new UserRepository();
$userService = new UserService($userRepository);
$userController = new UserController($userService);
echo $userController->showUser(1) . PHP_EOL; // Output: User ID: 1, Name: John Doe, Email: john.doe@example.com
echo $userController->showUser(3) . PHP_EOL; // Output: User not found.
?>