Page Expire - How to keep in cach from post request !!!

Question

I have a big problem with the back button resulting in Page Expired message. The system framework is to call servlets from any page. A servlets will perform necessary computations and forward the request with additional objects to a jsp page, which will in turn construct the page and display it to a user. Some of the constracted pages have back button, which simply redirects to the previous page.
The problem that I have has been described in multiple forums before, but still appears to be not solved. When I press the back button that shall display previous page, generated by the Post request, I get Page Expired message. Note that this occurs only in IE (I am using 6.0 with SP1) and not in Mozilla (I am using 1.3). I did my homework and tried the following code in different combinations, but unsuccessful:
resp.setHeader("Cache-Control", "public");
res.setHeader("Pragma", "Cache");
res.setHeader("Expires", "Fri, 30 May 2003 12:00:00 GMT");
or directly in jsp page
<META HTTP-EQUIV="Pragma" CONTENT="cache">
<META http-equiv="expires" CONTENT=" Fri, 30 May 2003 12:00:00 GMT ">
None seems to work in IE. It appears that the IE refuses to cache the page generated by the post request at all times.
The application that I am working is huge and this is a big problem for us, we need to support IE with back buttons.
Please help.

Answer 1

I believe this is a requirement of the HTTP
specification.Yep - section 13.10 for anyone who can't sleep. I believe the idea is that methods such as POST, PUT and DELETE cause an update at the server and so caching makes no sense - the client needs to view a new copy.
To quote the spec:
Some HTTP methods MUST cause a cache to invalidate an entity. This is either the entity referred to by the Request-URI, or by the Location or Content-Location headers (if present). These methods are:
- PUT
- DELETE
- POST