Which REST operation is most commonly idempotent according to typical REST principles?

Which REST operation is most commonly idempotent according to typical REST principles?

• A. POST /resource to create a new resource
• B. GET /resource/{id}
• C. PATCH /resource/{id}
• D. DELETE /resource/{id}

Answer: (B)

Idempotence means performing the same request multiple times has the same effect as doing it once, with no extra changes to server state after the initial application. GET /resource/{id} fits this idea perfectly because it just retrieves data and does not modify anything on the server. Repeating the same GET request will fetch the same resource (assuming the resource hasn’t changed in the meantime), so there are no side effects from multiple calls. The other options involve state changes: creating a resource with a POST typically creates a new item each time you call it; applying a PATCH can alter data and may not yield the same result on repeated calls; deleting removes the resource and, while subsequent DELETE requests don’t change state beyond the first, the first call already changes the server state by removing the resource. Among these, GET is the clearest, most reliable example of an idempotent operation.

Idempotence means performing the same request multiple times has the same effect as doing it once, with no extra changes to server state after the initial application. GET /resource/{id} fits this idea perfectly because it just retrieves data and does not modify anything on the server. Repeating the same GET request will fetch the same resource (assuming the resource hasn’t changed in the meantime), so there are no side effects from multiple calls.

The other options involve state changes: creating a resource with a POST typically creates a new item each time you call it; applying a PATCH can alter data and may not yield the same result on repeated calls; deleting removes the resource and, while subsequent DELETE requests don’t change state beyond the first, the first call already changes the server state by removing the resource. Among these, GET is the clearest, most reliable example of an idempotent operation.