System Design

Full outline

The architecture skills senior engineers are hired for: capacity estimation, data modelling, caching and queues, consistency trade-offs, resilience patterns, and how to communicate a design under interview pressure.

1. 01Building Blocks

   The components every design is assembled from.

   • Back-of-envelope estimation

     Turning vague requirements into numbers, so the design has constraints to satisfy.

   • Load balancing & proxies

     Distributing traffic, terminating TLS, and routing intelligently.

   • Storage selection

     Picking the store that matches the access pattern, not the one that's fashionable.

   • Caching layers

     Where to cache, what to cache, and how to invalidate it.

2. 02Scaling & Consistency

   What breaks when one machine becomes a hundred.

   • Replication & partitioning

     Copying data for availability; splitting it for capacity.

   • Consistency models

     Strong, eventual, causal — and what each one costs.

   • Messaging & event-driven design

     Decoupling services through queues and logs.

   • Failure & resilience

     Designing for the failure that will definitely happen.

3. 03Practice & Communicate

   A design nobody understands is not a design.

   • Classic case studies

     Work through the canonical problems until the patterns become instinct.

   • The interview framework

     A repeatable structure that stops you from rambling.

   • Reasoning about trade-offs

     Seniority is visible in how you justify a choice, not in how many buzzwords you use.