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safe reload POST?

From: Larry Masinter <masinter@parc.xerox.com>
Date: Tue, 24 Sep 1996 17:23:48 PDT
To: http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
Message-Id: <96Sep24.172348pdt."2759"@golden.parc.xerox.com>
After doing a case analysis ("original request failed", "original
request succeeded") x ("reload with warning", "reload without
warning"), I came up with the following proposal:

a) new optional request header that marks a request
   (GET, POST, etc.) as an 'unwarned retry'. This header might be
   generated by requests from pressing [Reload] on a browser.
   Syntax? (dunno).

b) new result header that marks whether a result
   is reloadable without warning, with three values:

   1) reloadable without warning (default for GET)
   2) not reloadable without warning (default for POST)
   3) not reloadable without warning, UNLESS reloading
      header (a) is supplied.

In the third case, it is the SERVER that decides whether a particular
reload is safe, or implements the warning.

It would still be the case that a POST which results in an error
(timeout, etc.) cannot be reloadable without warning, and that for
some HTML forms. It's a minor point, but equivalent GET form would be
reloadable without warning. (e.g., "search form to heavily loaded
server").

Note that I'm avoiding the ratsnest of "idempotent" and "cachable".

Is a bookmark a 'reload'?

Larry
Received on Tuesday, 24 September 1996 17:28:08 EDT

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