The Computing Series

The 15 Principles — Layer 1 (Recall Triggers)

# Principle One-Line Definition
P1 Abstraction Hide irrelevant complexity; expose only what callers need
P2 Modularity Units that can be developed, tested, and deployed independently
P3 Composability Small pieces that combine without surprising interactions
P4 Separation of Concerns Each component has one clear responsibility
P5 Idempotency The same operation applied twice has the same effect as once
P6 Reproducibility The same inputs produce the same outputs, every time
P7 Immutability Once created, data does not change; only new versions are created
P8 Locality Data and compute live close together; avoid unnecessary network hops
P9 Fault Tolerance The system continues operating correctly when components fail
P10 Observability You can tell what the system is doing from the outside
P11 Consistency The system behaves the same way under the same conditions
P12 Security Boundaries Trust is not assumed; it is verified at every crossing
P13 Fail Fast Detect errors early and stop rather than propagating incorrect state
P14 Least Privilege Every component has only the access it needs to do its job
P15 Measure & Adapt Systems are improved empirically, not by assumption

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