implement-stateless-idempotency

Idempotency in stateless distributed services is implemented by wrapping request handlers with idempotent middleware and a backing store to detect duplicates, manage TTLs, and ensure deterministic outcomes across retries.

Concurrent writes and event deduplication are handled using upsert semantics and conditional writes within your idempotency storage patterns, preventing duplicate event processing and ensuring consistent results across distributed systems.

Protecting critical operations like payment retries involves applying idempotent middleware to derive a key from requests, storing IdempotencyRecords with TTLs, and implementing complete or fail paths to block duplicate execution.

Configuring an IdempotentHandler requires wrapping your request handlers, wiring a backing IdempotencyStore, providing a key function to derive idempotency keys from requests, and implementing the described complete and fail paths.

No specific database is mandated; any backing IdempotencyStore that supports upsert semantics, conditional writes, and TTL management is sufficient for event deduplication in event-driven architectures.

Stateless idempotency in message queue processing relies heavily on the backing store's consistency for conditional writes and TTLs, requiring robust testing practices to ensure deterministic outcomes during concurrent event deduplication.