CODESAMPLE

Microservices - Swift

Microservices Swift

The Microservices pattern structures an application as a collection of loosely coupled, independently deployable services, modeled around a business domain. Each service owns its data and communicates via lightweight mechanisms, often a RESTful API. This example demonstrates a simplified implementation with two services: UserService and OrderService. They communicate through a shared User model and a basic API client. Swift’s protocol-oriented programming and strong typing lend themselves well to defining clear service interfaces. Using Codable for data transfer is idiomatic for handling JSON in Swift. The structure favors composition over inheritance, aligning with microservice principles.

// Shared Model
struct User: Codable {
    let id: Int
    let name: String
}

// UserService
protocol UserService {
    func getUser(id: Int) async throws -> User
}

class UserServiceImpl: UserService {
    func getUser(id: Int) async throws -> User {
        // Simulate database call
        if id == 1 {
            return User(id: 1, name: "Alice")
        } else {
            throw NSError(domain: "UserService", code: 404, userInfo: [NSLocalizedDescriptionKey: "User not found"])
        }
    }
}

// OrderService
protocol OrderService {
    func createOrder(userId: Int) async throws -> String
}

class OrderServiceImpl: OrderService {
    private let userService: UserService

    init(userService: UserService) {
        self.userService = userService
    }

    func createOrder(userId: Int) async throws -> String {
        let user = try await userService.getUser(id: userId)
        // Simulate order creation
        let orderId = UUID().uuidString
        return "Order \(orderId) created for \(user.name)"
    }
}

// API Client (Simplified)
actor APIClient {
    private let userService: UserService
    private let orderService: OrderService

    init(userService: UserService, orderService: OrderService) {
        self.userService = userService
        self.orderService = orderService
    }

    func getUserName(userId: Int) async throws -> String {
        let user = try await userService.getUser(id: userId)
        return user.name
    }

    func placeOrder(userId: Int) async throws -> String {
        return try await orderService.createOrder(userId: userId)
    }
}

// Example Usage
func main() async {
    let userService = UserServiceImpl()
    let orderService = OrderServiceImpl(userService: userService)
    let apiClient = APIClient(userService: userService, orderService: orderService)

    do {
        let userName = try await apiClient.getUserName(userId: 1)
        print("User name: \(userName)")

        let orderConfirmation = try await apiClient.placeOrder(userId: 1)
        print(orderConfirmation)
    } catch {
        print("Error: \(error)")
    }
}

Task {
    await main()
}