Architecture & Design Patterns

How software systems are structured for maintainability, testability, and scale — from SOLID principles to advanced DDD and event sourcing.

OOP Pillars

SOLID

Clean Arch

DDD

Repository

CQRS

Event Sourcing

Mediator

GoF Patterns

Decorator

Anti-Patterns

Foundation

SRP, OCP, LSP, ISP, DIP — with real C# and TypeScript code examples.

Encapsulation, Inheritance, Polymorphism, Abstraction — beyond the textbook.

Architecture

Layers, dependency rule, use cases, and how to structure a real project.

Aggregates, entities, value objects, bounded contexts, and ubiquitous language.

Design Patterns

Data access abstraction, transaction boundaries, and testability.

Command/Query split, event stores, and rebuilding state from events.

Request/handler pipeline, decoupled handlers, and pipeline behaviors.

Gang of Four patterns you'll use every day in production code.

The middleware pattern — cross-cutting concerns like logging and caching.

Quality

God object, service locator, over-engineering — what NOT to do.