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Idempotency

Idempotency in the context of APIs refers to the property of certain HTTP methods where performing the same operation multiple times has the same effect as performing it once. In other words, if a request is idempotent, making multiple identical requests will not produce different outcomes than making a single request.

For example, consider a hypothetical API endpoint for updating a user's profile information:

  • If the API endpoint is idempotent, sending the same request to update the user's profile multiple times with the same data will result in the same state of the user's profile each time.
  • If the API endpoint is not idempotent, sending the same request multiple times might result in unintended consequences, such as creating duplicate records or modifying the data in unexpected ways.

Idempotent HTTP methods include:

  1. GET: Retrieving data from the server. Sending multiple identical GET requests will not modify the server's state.

  2. PUT: Updating or replacing a resource at a specific URI. Repeated PUT requests with the same data will have the same effect as a single request.

  3. DELETE: Deleting a resource at a specific URI. Deleting a resource multiple times will result in the resource being deleted only once.

Idempotency is an important concept in API design and implementation, as it helps ensure predictable behavior and reliability of APIs, especially in scenarios where requests might be retried due to network issues or other failures. By designing idempotent APIs, developers can minimize unintended side effects and make systems more robust and resilient.