chickadee » intarweb » idempotent?

idempotent? request-or-methodprocedure

Returns #t when the given request object or symbol (method) is a idempotent method. A method is defined to be idempotent when a series of identical requests of this method in succession causes the exact same side-effect as just one such request. In practice this means that you can safely retry such a request when an error occurs, for example.

Important: Just as with the safe methods, there is no guarantee that methods that should be idempotent really are idempotent in any given web application. Furthermore, a sequence of requests which each are individually idempotent is not necessarily idempotent as a whole. This means that you cannot replay requests starting anywhere in the chain. To be on the safe side, only retry the last request in the chain.