How do you handle Cross-Cutting Concerns (Logging, Caching, Authentication) without polluting business logic? (AOP/Proxy/Decorator)
Separating Cross-Cutting Concerns
Cross-cutting concerns should be separated from core business behavior. Depending on the platform, I can use middleware, decorators, proxies, interceptors, filters, or AOP. Dependency injection is usually the foundation because it allows business services to depend on abstractions while infrastructure concerns are composed around them.
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Middleware is suitable for HTTP/request pipeline concerns.
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Decorators are useful when behavior needs to wrap a particular service.
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AOP/interceptors can centralize repetitive cross-cutting behavior.
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Authentication and authorization should normally be enforced at appropriate security boundaries.
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Caching should be applied deliberately based on consistency and invalidation requirements.
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Cross-cutting abstractions should not hide important business behavior or make debugging unnecessarily difficult.
Follow-up Questions
- When would you prefer middleware over decorators?
- How would you prevent caching stale data?
- Where should authorization be enforced?