📌 Use Cases in Clean Architecture and ConnectSoft

ConnectSoft enables a wide spectrum of use cases — from clean architecture orchestration to template-based delivery of SaaS platforms and AI-enhanced services. This document covers how use cases are realized within Clean Architecture and provides applied examples using ConnectSoft’s platform ecosystem.

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🧠 What is a Use Case?

In Clean Architecture, a Use Case represents an application-specific workflow — encapsulating business logic that coordinates domain models and external interactions without embedding technical dependencies.

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In ConnectSoft, use cases sit at the Application Layer and are invoked by controllers, queues, or schedulers. They handle orchestration, enforce domain rules, and delegate to aggregates or services.

A use case:

• Encapsulates one business operation
• Coordinates repositories, domain models, and external systems
• Remains framework-agnostic and stateless

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🗱 Design Principles for Use Cases

Principle	Explanation
✅ Single Responsibility	Focus on a single business operation or flow
🔀 Stateless	Avoid internal state to maximize reusability
🌟 Orchestration	Coordinate aggregates, value objects, and services
📦 DTO Usage	Use DTOs for all input/output to ensure separation
🔐 Transaction Scope	Enforce transactional boundaries for domain operations

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🧪 Example: PlaceOrderUseCase

public class PlaceOrderUseCase
{
    private readonly IOrderRepository _orderRepository;
    private readonly IInventoryService _inventoryService;
    private readonly INotificationService _notificationService;
    private readonly IUnitOfWork _unitOfWork;

    public PlaceOrderUseCase(
        IOrderRepository orderRepository,
        IInventoryService inventoryService,
        INotificationService notificationService,
        IUnitOfWork unitOfWork)
    {
        _orderRepository = orderRepository;
        _inventoryService = inventoryService;
        _notificationService = notificationService;
        _unitOfWork = unitOfWork;
    }

    public async Task Execute(PlaceOrderDto input)
    {
        using (var transaction = _unitOfWork.BeginTransaction())
        {
            foreach (var item in input.Items)
            {
                if (!await _inventoryService.IsInStock(item.ProductId, item.Quantity))
                {
                    throw new InvalidOperationException($"Product {item.ProductId} is out of stock.");
                }
            }

            var order = new Order(input.CustomerId);
            foreach (var item in input.Items)
            {
                order.AddItem(item.ProductId, item.Quantity);
            }

            _orderRepository.Add(order);

            foreach (var item in input.Items)
            {
                await _inventoryService.ReserveStock(item.ProductId, item.Quantity);
            }

            await _notificationService.SendOrderConfirmation(input.CustomerId, order.Id);

            transaction.Commit();
        }
    }
}

🔄 Sequence: Place Order

sequenceDiagram
    participant User
    participant UseCase as PlaceOrderUseCase
    participant Domain as OrderAggregate
    participant Inventory as InventoryService
    participant Notification as NotificationService

    User->>UseCase: Submit Order
    UseCase->>Domain: Create Order
    UseCase->>Inventory: Reserve Stock
    UseCase->>Notification: Send Confirmation

Hold "Alt" / "Option" to enable pan & zoom

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📌 Real-World Use Cases

🛍 E-Commerce

• Use Case: PlaceOrder
• Workflow: Validate inventory → Create order → Update stock → Notify customer.

  sequenceDiagram
      participant UI
      participant UseCase as PlaceOrderUseCase
      participant Order as OrderAggregate
      participant Inventory as InventoryService
      participant Notification as NotificationService
  
      UI->>UseCase: Submit Order
      UseCase->>Order: Validate + Create
      UseCase->>Inventory: Reserve Items
      UseCase->>Notification: Send Email

  Hold "Alt" / "Option" to enable pan & zoom

🏥 Healthcare

• Use Case: ScheduleAppointment
• Workflow: Check provider availability → Create appointment → Notify stakeholders.

  sequenceDiagram
      participant User
      participant UseCase as ScheduleAppointmentUseCase
      participant Calendar as AppointmentAggregate
      participant Notification as NotificationService
  
      User->>UseCase: Request Slot
      UseCase->>Calendar: Reserve Time
      UseCase->>Notification: Confirm Slot

  Hold "Alt" / "Option" to enable pan & zoom

💳 Finance

• Use Case: TransferFunds
• Workflow: Validate balance → Debit source → Credit target → Record transaction.

  sequenceDiagram
      participant User
      participant UseCase as TransferFundsUseCase
      participant Account as AccountAggregate
  
      User->>UseCase: Transfer Request
      UseCase->>Account: Withdraw from Source
      UseCase->>Account: Deposit to Target

  Hold "Alt" / "Option" to enable pan & zoom

🤖 AI

• Use Case: RunSemanticInference
• Workflow: Accept prompt → Generate result via AI → Save result for traceability.

  sequenceDiagram
      participant Trigger
      participant UseCase as SemanticKernelUseCase
      participant Kernel as SemanticAgent
      participant Store as LogStore
  
      Trigger->>UseCase: Send Prompt
      UseCase->>Kernel: Generate Completion
      UseCase->>Store: Save Result

  Hold "Alt" / "Option" to enable pan & zoom

⚙️ DevOps

• Use Case: DeployService
• Workflow: Validate infrastructure → Provision cloud resources → Trigger CI/CD deploy.

  sequenceDiagram
      participant CLI
      participant UseCase as DeploymentUseCase
      participant Pulumi as PulumiService
      participant CI as AzurePipelines
  
      CLI->>UseCase: Deploy Request
      UseCase->>Pulumi: Provision Resources
      UseCase->>CI: Push Build + Deploy

  Hold "Alt" / "Option" to enable pan & zoom

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🔹 Best Practices for Use Cases

1. Keep Stateless

   • Avoid storing state inside the use case class.

2. Use DTOs

   • Encapsulate input/output in well-structured data contracts.

3. Enforce Business Rules via Domain

   • Delegate validations and calculations to aggregates or domain services.

4. Define Transaction Scope

   • Ensure that all actions inside a use case are part of a single transactional unit.

5. Write Tests for All Flows

   • Unit test the use case logic and integration test real services with stubs/mocks.

6. Avoid Infrastructure Dependencies

   • Use ports and abstractions to isolate framework interactions.

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✅ Conclusion

Use cases are the critical bridge between business needs and system behavior. Within Clean Architecture, they enable strict separation of concerns, centralized workflow control, and clear interfaces for input and output.

At ConnectSoft, use cases are more than a pattern — they're a first-class citizen in our platform and templates. Every solution we offer ensures that your workflows are stateless, testable, and decoupled from infrastructure. Whether you are building a SaaS product, integrating an AI engine, or automating deployments, the use case layer is your safest and most scalable foundation.

By combining Clean Architecture with DDD, event-driven messaging, and modular templates, ConnectSoft ensures that use cases are:

• 🔧 Easy to implement
• 🔄 Easy to test and evolve
• 🔐 Isolated from volatile infrastructure concerns
• 📈 Ready for production, at any scale

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📊 References

• Clean Architecture in .NET
• ConnectSoft Microservice Template
• ConnectSoft SaaS Offerings
• Domain-Driven Hexagon Architecture
• Use Cases in Software Design

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Explore more in Clean Architecture and Microservice Template Use Cases.