Which HTTP method is appropriate for canceling a booking and is idempotent?

Which HTTP method is appropriate for canceling a booking and is idempotent?

• A. GET
• B. POST
• C. DELETE
• D. PATCH

Answer: (C)

Idempotence means sending the same request multiple times has the same effect as sending it once. Canceling a booking fits this idea when done by removing the booking resource with a delete operation: the first request cancels the booking, and any subsequent identical requests simply find that the booking is already gone, causing no extra changes. Other methods aren’t as well suited for this use case. Retrieving data with the retrieving method should not change state, so it’s not appropriate for cancellation. Submitting with the creating-action method often leads to additional side effects or repeated creations, which isn’t what you want for canceling. Partially updating with the partial-update method could achieve cancellation if you consistently set a canceled status, but that relies on how the service defines and handles partial updates, and delete is the clearest, most predictable way to remove the booking.

Idempotence means sending the same request multiple times has the same effect as sending it once. Canceling a booking fits this idea when done by removing the booking resource with a delete operation: the first request cancels the booking, and any subsequent identical requests simply find that the booking is already gone, causing no extra changes.

Other methods aren’t as well suited for this use case. Retrieving data with the retrieving method should not change state, so it’s not appropriate for cancellation. Submitting with the creating-action method often leads to additional side effects or repeated creations, which isn’t what you want for canceling. Partially updating with the partial-update method could achieve cancellation if you consistently set a canceled status, but that relies on how the service defines and handles partial updates, and delete is the clearest, most predictable way to remove the booking.