Implementing Idempotency for API Requests in Backend Development

Discusses the importance of scaling systems and the two main directions: hardware architecture improvements using cloud services such as load balancers (SLB), cloned ECS instances, RDS databases, and OSS storage; and software architecture optimizations including business decoupling, micro‑services, stateless design, and shared file storage.

Introduces the concept of idempotency, defining its effect (the system should return the same result for multiple requests to the same interface, except when network failures occur) and its purpose (to avoid duplicate business processing caused by repeated requests).

Idempotency Scenarios

Examples of duplicate request situations include: (1) the client’s first request succeeds on the server but the response is lost due to a network error, prompting the client to retry; (2) the user rapidly clicks a submit button, sending the same request multiple times.

Explains that read‑only operations (queries) are naturally idempotent, delete operations generally do not cause data inconsistency, while create and update operations need safeguards to prevent duplicate inserts or unnecessary repeated updates.

Implementation Methods

Suggests that the client include a unique identifier with each request; the server checks this identifier, caches the result keyed by it, and returns the cached response for any subsequent identical requests.

Provides an example where an AddId is generated when opening an add‑form, submitted together with the form data, and used by the backend to filter duplicate submissions; the AddId is refreshed only after a successful save and form reset, ensuring new data submissions are correctly identified.