Designing Idempotent Retail APIs: Preventing Duplicate Orders During Retries
A customer places an order. The ERP creates it, but the connection drops before the ecommerce platform receives confirmation. The ecommerce platform retries the request. Should the ERP create another order? This is a common challenge in retail integration. A timeout tells the client that it did not receive a response. It does not tell the client whether the operation succeeded. This article…
A customer places an order, but the connection between systems drops before the ecommerce platform receives confirmation. The platform retries the request, potentially creating duplicate orders. An idempotent API prevents this issue by ensuring repeated requests produce the same effect as a single request. An idempotency key, generated by the client and persisted, allows the server to recognize and handle retries without creating additional orders.
Define a request contract that specifies how the API should behave when encountering duplicate keys. Store the idempotency key with the corresponding result in a database table, using request hashes to identify equivalent requests. Implement atomic transactions to create the order and save the idempotency record simultaneously, ensuring consistency even if the process is interrupted.
Protect downstream operations by ensuring that creating an order locally does not inadvertently trigger duplicate work elsewhere.
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