Idempotenssiavaimia

Idempotenssiavaimia, or idempotency keys, are a mechanism used in API design to ensure that repeated identical requests have the same effect as a single request. This is particularly useful for operations that modify data or trigger side effects, where a network glitch or client-side retry could unintentionally lead to duplicate actions. An idempotency key is typically a unique identifier, often a UUID, generated by the client for each distinct operation. The server stores this key along with the result of the operation. When a subsequent request arrives with the same idempotency key, the server recognizes it as a duplicate and returns the previously computed result without re-executing the operation.

The implementation of idempotency keys typically involves the client sending the key in a request header, such as `Idempotency-Key`. The server then checks if a record exists for that key. If it does, it returns the stored response. If it does not, the server processes the request, stores the key and its associated response, and then returns the response to the client. This ensures that even if the client retries a request multiple times due to network issues, the underlying operation on the server is only performed once, preventing unwanted side effects like double charges or duplicate resource creation. This concept is crucial for building robust and reliable distributed systems.