CODESAMPLE

SOA - Dart

SOA Dart

The Service-Oriented Architecture (SOA) pattern structures an application as a collection of loosely coupled, independent services. Each service encapsulates a specific business function and communicates with others through well-defined interfaces (often APIs). This promotes modularity, reusability, and independent deployment.

The Dart example demonstrates a simplified SOA with UserService and ProductService. Each service has a clear responsibility: managing user data and product information, respectively. They expose methods for interacting with their data. A ServiceClient orchestrates calls to these services. Using classes and interfaces is idiomatic Dart for structuring such components, enabling clear separation of concerns and testability. The use of asynchronous methods (Future) reflects Dart’s preferred approach for handling I/O and network operations common in SOA.

// user_service.dart
abstract class UserService {
  Future<String> getUserName(int userId);
}

class DefaultUserService implements UserService {
  final Map<int, String> users = {1: 'Alice', 2: 'Bob'};

  @override
  Future<String> getUserName(int userId) async {
    await Future.delayed(Duration(milliseconds: 50)); // Simulate network latency
    return users[userId] ?? 'Unknown User';
  }
}

// product_service.dart
abstract class ProductService {
  Future<double> getProductPrice(String productId);
}

class DefaultProductService implements ProductService {
  final Map<String, double> products = {'A123': 19.99, 'B456': 29.99};

  @override
  Future<double> getProductPrice(String productId) async {
    await Future.delayed(Duration(milliseconds: 100)); // Simulate network latency
    return products[productId] ?? 0.0;
  }
}

// service_client.dart
class ServiceClient {
  final UserService userService;
  final ProductService productService;

  ServiceClient({required this.userService, required this.productService});

  Future<String> getOrderDetails(int userId, String productId) async {
    final userName = await userService.getUserName(userId);
    final productPrice = await productService.getProductPrice(productId);

    return '$userName ordered product $productId for \$${productPrice.toStringAsFixed(2)}';
  }
}

// main.dart
import 'user_service.dart';
import 'product_service.dart';
import 'service_client.dart';

void main() async {
  final userService = DefaultUserService();
  final productService = DefaultProductService();
  final client = ServiceClient(userService: userService, productService: productService);

  final orderDetails = await client.getOrderDetails(1, 'A123');
  print(orderDetails); // Output: Alice ordered product A123 for $19.99
}