← Principles
Command-Query Separation
Every method should be either a command that performs an action or a query that returns data, but not both. Improves clarity and predictability of code.
4 Lessons
Knowledge Course
01
Command Query Separation: Mutations and Reads Never Mix
Why methods that both change state and return values create the worst bugs.
45 min→
02CQS in Production: APIs and Services
Applying CQS to REST APIs, service methods, and read/write scaling.
60 min→
03Advanced CQS: CQRS and Event Sourcing
Full command/query responsibility segregation with read models and event sourcing.
75 min→
04CQS: Review & Mastery Quiz
Scenario questions on command/query separation across levels.
quiz30 min→
Curated Resources
Free Books & Guides
Official Documentation
Video Courses
Command-Query Separation — Explained (YouTube)
A video explanation of the Command-Query Separation principle with practical examples.
freeCodeCamp — Software Architecture Course
A comprehensive course covering software architecture principles, patterns, and best practices.
ByteByteGo — Distributed Systems
High-quality animated explanations of system design principles, distributed systems, and architecture patterns.