xmlhttp and ie cache

[Jack Clift]

I am using xmlhttp.open and .send to retreive data from the internet. This
works ok but I have realised that the data retreived is not refreshed from
the web server, rather is being taken from ie cache (meaning that the data is
effectively useless).

I have tried using .setrequestheaders with a variety of options. This did
not work.

Clearing the cache does force a requery of the web server, but is not a
practical solution.

I have found one suggestion in seaches on the web that indicated a registry
setting be changed before the query, and then reset after - seems a bit
drastic for mine.

Is there a simpler solution to this?

thanks

JC

 

[Robin Hammond]

Jack,

Yes, massively simpler. Add a dummy parameter to your post and change the
dummy value to force a refresh.

e.g. something like
strPost = http://nnn.nnn.nnn.nnn/MyPage.asp?Param1=55&Param2= &
int(rand()*1000)

Robin Hammond
www.enhanceddatasystems.com

 

[Robin Hammond]

that should be
CInt(1000 * Rnd())

Robin Hammond
www.enhanceddatasystems.com

 

[Jack Clift]

Thanks Robin, have written small slice of code that submits a date string
(year, month, day, hour, minute, second), was easiest for me to do it that
way.

Works fine.

Am interested though on the origninal problem - is this a problem on the
server (web) side or something problematic with xmlhttp? Just curious for
future reference.

Cheers

JC

 

[Tim Williams]

A general "feature": I think IE's cache is also shared by other objects such
as xlmhttp. If the caching algorithm sees you making a request you've
recently made (how recently being determined by your cache settings) then
instead of making a request to the server it will simply fetch the content
from the cache. A proxy server may also do the same thing regardless of
your local settings.

Since the request "identity" is based on the URL including the querystring,
the "random" parameter will side-step the cache issue.

Tim.