login problems

[penagate]

The 303 status code instructs the user agent not to cache the response and to follow up the resource specified in the Location header. The reason for redirection after handling a POST request is to avoid the annoying "Do you want to resend the data" message that occurs if the user navigates back then forward or refreshes the page. The 303 redirection means that the page is not cached and so this problem does not occur. You should always use this approach to handling posted data; if not, it is easy for the user to accidentally perform a POST action twice, which can have severe consequences (for example, if that action is to delete some data).