What if the underlying data has changed?
If I QUERY the current price of a stock, and then someone else sends an identical QUERY ten seconds later, they might get a different result. This is not because QUERY isn't idempotent.
If I QUERY the current price of a stock, and then someone else sends an identical QUERY ten seconds later, they might get a different result. This is not because QUERY isn't idempotent.
rfc2616 says:
> Methods can also have the property of "idempotence" in that (aside from error or expiration issues) the side-effects of N > 0 identical requests is the same as for a single request.
https://datatracker.ietf.org/doc/html/rfc2616#page-51
Perhaps changes in the underlying data could be considered "expiration issues". Otherwise not even GET could be considered idempotent in many cases.
That's why it's called idempotent - 'doing the same' - rather than impotent.
If a request changes the state of the server and another identical request changes the state of the server in a different way, it's not idempotent.
If a request doesn't change the state of the server at all it is idempotent, even if subsequent requests might get different responses (e.g. the stock quote example in my previous post).
If a request changes the state of the server but repeated identical requests don't have any different effect it is also idempotent. For example, DELETE is idempotent because DELETE-ing something N times is the same as deleting it one time.
“Obsoleted by: 7230, 7231, 7232, 7233, 7234, 7235”