Module 8: Leadership & System Design

Senior developers and engineering leaders must go beyond writing code: they must think in systems, mentor others, and make strategic technical decisions.

System design diagram on a whiteboard

Beyond a Single Class: Thinking in Systems

As your career grows, your responsibility shifts from implementing features to designing the systems that contain them. System design is the art of defining architecture, components, modules, interfaces, and data to meet functional and non-functional requirements.

Key Concepts You Must Understand

Vertical scaling adds resources (CPU, RAM) to a single server. Horizontal scaling adds more servers to a cluster. Modern cloud-native systems prioritize horizontal scaling for resilience and performance.

Load balancers distribute traffic across multiple servers, preventing overload and ensuring high availability. Understanding different algorithms (round-robin, least connections) is important for designing robust systems.

Caching stores frequently accessed data in high-speed storage like Redis or Memcached to reduce database load and improve latency. Know cache invalidation strategies and expiration policies.

For long-running tasks (emails, video processing), use message queues (RabbitMQ, SQS) with background workers. This decouples services and improves user experience. Understand concepts like retries, dead-letter queues, and idempotency.

Leadership & Career Growth

Technical skill alone is not enough. Senior developers and engineering leaders must also mentor, guide technical decisions, and influence team culture.