HTTP POST and HTTP GET

An HTML template can be requested with either of the following operations:

• POST

  Pages generated by an HTTP POST operation are always cached. The Web browser uses POST operations whenever an HTML FORM statement specifies METHOD="POST".

• GET

  Pages generated by GET operations are never cached because the Internet Transaction Server (ITS) explicitly sets a no-cache option in the HTTP header when the page is sent to the Web browser. It does not matter which caching options are set in the Web browser. The Web browser uses GET operations for hypertext links and FRAMESET documents.

If the target page was generated by a POST operation, the ITS does not synchronize immediately because the page is retrieved from the Web browser cache. Only if the cached page issues a POST or GET operation to a non-cached page does the ITS perform the synchronization.

The type of HTTP operation determines when the ITS requests synchronization. Whenever the user navigates with the Web browser's Back button or History function, and the target page was generated by a GET operation, the ITS synchronizes immediately.

The following diagram shows such an example: The ITS does not synchronize when the user navigates back to the overview screen. Only if the user again requests a detail screen from the overview screen will the ITS be able to synchronize.