Milt's answer is correct, here's some code. Place this code between the
<HEAD></HEAD> tags in your JSP page.
<%
out.println("<META HTTP-EQUIV=\"expires\" CONTENT=\"1996-01-01\">");
out.println("<META HTTP-EQUIV=\"Cache-Control\" CONTENT=\"no-cache\">");
out.println("<META HTTP-EQUIV=\"Pragma\" CONTENT=\"no-cache\">");
%>
BTW, using the servlet api methods to do this did not seem to work for me
(using Jrun) so I resorted to the out.println .
Mike Fontenot
> Does anyone out there know the correct syntax to set the Expires
> header? I cannot seem to get it to work correctly and cannot find any
> examples on the internet?
>
> Thanks,
> Jaman
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
> Sent: Monday, August 23, 1999 5:37 PM
> To: [EMAIL PROTECTED]
> Subject: Re: BACK-ing into trouble
>
>
> On Mon, 23 Aug 1999, Jaman Burton wrote:
>
> > Any assistance would be greatly appreciated in this matter...
> >
> > In the midst of developing our internet site using HTTPSessions I've
> > discovered that when a user employs the use of a browser's "BACK"
> > button they can unwittingly bring themselves to one of our error
> > pages.
> >
> > Although this outcome, isn't harmful to us or our users, it is
> > unwanted. Is there a way that the "BACK" button can be disabled
> > within a servlet or if not, I have seen sites were it seems as
> > though pages won't let you "BACK" into them...how is this
> > accomplished?
>
> Questions like these seem to come up from time to time. I don't have
> a specific answer for you, but perhaps thinking about how the BACK
> button works might help you. If I have any of this wrong, please
> correct me.
>
> The BACK button is pure browser, i.e. client-side, functionality. As
> such, it is out of direct server-side control. All it does is recall
> the previous (or the nth previous) URL, and perhaps re-request it
> (i.e. it is really no different than if the user typed in that URL).
> I say "perhaps" because it is subject to caching considerations -- if
> the client has cached the URL in question, it will just display the
> cached version, without re-requesting it. That means you really won't
> be able to do anything about it, since the server isn't being
> contacted.
>
> >From the server-side you do have some control over whether a page is
> cached, though, which may give you enough indirect control of what
> happens when the BACK button is pressed to restrict things as you
> want. Notice I say "may", because supposedly not all browsers obey
> the headers you use to indicate that you don't want the page cached
> (everything's full of caveats :-).
>
> So, for example, you could set things up such that the pages in
> question are not cached, and use sessions and such to store enough
> info about the user's session, and thus detect and control what
> happens when the BACK button is pressed.
>
> Here's what I've heard to use to get browsers to not cache a page (it
> was recommended to use all of them):
>
> 1. Set the Expires header to some date in the past (far in the past,
> so you don't get screwed up by a clock that's five minutes off)
>
> 2. Set the Cache-Control header to "no-cache"
>
> 3. Set the Pragma header to "no-cache"
>
> Hope this helps.
>
> Milt Epstein
> Research Programmer
> Software/Systems Development Group
> Computing and Communications Services Office (CCSO)
> University of Illinois at Urbana-Champaign (UIUC)
> [EMAIL PROTECTED]
>
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========================================
Mike Fontenot - Object Systems Architect
Polygon Network, Inc.
Golden, CO
========================================
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