Exploring the Open‑Closed Principle in Software Architecture to Reduce Cognitive Load and Improve Efficiency

Software design quality heavily influences later operation, iteration cost, and risk, particularly for high‑frequency internet business systems; this piece investigates how the open‑closed principle can reduce programmer cognitive load and improve efficiency.

It first lists common R&D doubts—such as the roles of business versus technology, the purpose of technology, lowering production incidents, maximizing ISV value, boosting developer productivity, avoiding "tar pits," and upgrading legacy systems—seeking a unified underlying logic.

By applying the open‑closed principle together with the single‑responsibility principle, the article argues for modular, extensible architectures, referencing the Phoenix architecture and drawing parallels between system evolution and biological evolution.

The Von Neumann architecture is highlighted as an early embodiment of the open‑closed principle, and modern SaaS/PaaS/IaaS models are presented as contemporary realizations of the same idea.

Further, it proposes a layered DDD approach where stable core services are separated from variable business functions, suggesting a "star‑link" style operating system to encapsulate stable domains and enable vertical expansion while maintaining clean boundaries.

In conclusion, the author advocates for "lego‑like" systems that isolate responsibilities, reduce cognitive load, and foster a culture of clean, evolvable software architecture.