Idempotency

Kind: principle

Layer: Atomic Boundary

Aliases: Idempotence

Record: architecture:idempotency

Severity: mandatory

Scope: API, command, message handler

Canonical: Ontology

A design rule that repeating an operation with the same input has the same effect as running it once.

Listed in Architecture principles, after Root Spine Files and before Atomicity.

Requires

• Idempotency Key or Deterministic Operation

Reinforces

• Retry Safety
• Event-Driven Architecture

Enables

• Safe Retries

Conflicts with

• Non-Repeatable Side Effects

In tension with

• State Tracking

Tensions

• Idempotency / State Tracking

Violated by

• Non-Idempotent Operation
• Duplicate Side Effects

Refactored by

• Idempotency Key
• Idempotent Consumer

Severity

• mandatory

Category

• Transactions / State / Concurrency

Enforced by

• codemods/entrypoints/sink.entrypoint.ts
• rules/eslint/no-raw-file-write.eslint.rule.ts

Required by

• Eventual Consistency
• Saga Pattern
• Retry Pattern

Enabled by

• Canonicalization

Linked from

• Posting and waiting are one operation
• Every record has a kind
• Computation and resource
• Event / Messaging / Asynchronous Architecture
• Error Handling / Resilience
• Schema / Canonical Data / Semantics
• Error Handling / Resilience
• Event Messaging Async
• Quality Attributes
• Transactions / State / Concurrency
• Severity levels
• The resolutions

in this codebase

• rules/eslint/no-raw-file-write.eslint.rule.ts