When to Use DI/SOA vs Simple Scripts

Use DI/SOA Pattern (Service-Oriented Architecture) For:

• Web Applications: Flask/FastAPI apps with multiple routes and services
• Background Workers: Celery tasks, async workers processing queues
• Microservices: Services with API endpoints and business logic
• Data Pipelines: ETL with multiple stages, transformations, and validations
• CLI Tools with Complexity: Multi-command CLIs with shared state and configuration
• Systems with External Dependencies: Apps requiring mock testing (databases, APIs, caches)
• Domain-Driven Design: Applications with complex business rules and aggregates

Benefits: Testability (mock dependencies), maintainability (clear separation), extensibility (swap implementations)