Re: Cache feature doesn't produce expected result (bug?)

Hi Juan,

I tried exactly the steps that you advised but this is where I can't reproduce

If you set HttpContext.Current.Response.Cache.SetAllowResponseInBrowserHistory(False)
you'll see that immediately the "This page has expired" message *is* displayed, and the client needs to resubmit the >page.

I dont see the "This page has expired" message and if I comment out SetAllowResponseInBrowserHistory I get the same result as False is the default. No "This page has expired" message, the browser request a new page as I can see by the time.

Could it be that you saw this when testing without restarting IE? I even made a video of my clean virtual machine (just SP2 installed) to show you my result.

Please try this:
http://users.pandora.be/TomPester/ASP/r.rar

Do you realy get a "This page has expired" when you do what's on the video? I don't.

Setting SetAllowResponseInBrowserHistory to true or false... I never see a difference.

Cheers,
Tom Pester


re:

You only need to set
HttpCachePolicy.SetAllowResponseInBrowserHistory when you need to
set it to true to override the NoCache setting

Setting SetAllowResponseInBrowserHistory to True doesn't
touch/override the "no-cache" value. It only removes the expires=-1
header.

Maybe we have a semantics problem here.

Removing the expires= -1 header *equals* overriding the "NoCache"
value.

When HttpCacheability is set to NoCache or ServerAndNoCache the
Expires HTTP header is set to -1 by default.

NoCache and ServerAndNoCache instruct the client to not cache
responses in the History folder by setting that header.

This means that each time you use the back/forward buttons, the client
requests a new version of the response.

When SetAllowResponseInBrowserHistory is set to True, the Expires HTTP
header is removed.

If you comment out this line :
HttpContext.Current.Response.Cache.SetAllowResponseInBrowserHistory(Tr
ue) and alternate between clicking the Submit button and the Back
button, you'll see that the "This page has expired" message is not
displayed.

That means that the client *has* requested a new version of the page,
without having to resubmit the page.

If you set
HttpContext.Current.Response.Cache.SetAllowResponseInBrowserHistory(Fa
lse) you'll see that immediately the "This page has expired" message
*is* displayed, and the client needs to resubmit the page.

Now, if you set
HttpContext.Current.Response.Cache.SetAllowResponseInBrowserHistory(Tr
ue)
and alternate between the Submit button and the Back button,
you'll see that the "This page has expired" message is not displayed,
and the page is displayed without needing to resubmit the page.
The documentation is wrong in requesting that you
"Click the Submit button a few times".
That throws a wrench into the works.
You should only hit it once to see the correct behavior.
The documentation is also wrong when it states that
SetAllowResponseInBrowserHistory allows client-side caching.

In effect all it does is remove the need to resubmit the page.

I hope this makes this issue clearer.

Juan T. Llibre
ASP.NET MVP
http://asp.net.do/foros/
Foros de ASP.NET en Español
Ven, y hablemos de ASP.NET...
======================
<Tom.PesterDELETETHISSS@xxxxxxxxxx> wrote in message
news:a1a977a22e56e8c742966a1df0de@xxxxxxxxxxxxxxxxxxxxx

Hi Juan,

Thanks for your response.

You only need to set
HttpCachePolicy.SetAllowResponseInBrowserHistory when you need to
set it to true to override the NoCache setting

Setting SetAllowResponseInBrowserHistory to True doesn't
touch/override the "no-cache" value. It only removes the expires=-1
header.

This code shows this :
Response.Cache.SetCacheability(HttpCacheability.NoCache)
Response.Cache.SetAllowResponseInBrowserHistory(True)

The servers send the following cache related headers :
'Cache-Control: no-cache
'Pragma: no - Cache
I don't know if you are experienced in http headers and their
behavior but could you please test the code that's on this page and
report your result? :

http://msdn2.microsoft.com/library/97wcd0a4(en-us,vs.80).aspx

If you run the sample and go back with your browser I think you will
find that the text on the page is wrong.

Thanks in advance, Tom



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