yes it does help. That's a simple and effective way.
thanks Scott & Ian.
Garth
At 10:53 22/07/02 -0700, you wrote:
>Hi Garth,
>
>Do like Ian does with TAF files. When making a fresh call to the image - to
>check that it made it - dynamically add an argument (to the filename) that
>contains a unique value each time.
>
>Example:
>
><img src="uploaded_images/emu.jpg?random=2349872394872" />
>
>MSIE believes it has to get a fresh copy because MSIE cache is typically
>based on the entire URL. Then IIS will serve up your image normally and the
>arguments are ignored.
>
>Hope this helps. Cheers...
>
>----- Original Message -----
>From: "Garth Penglase" <[EMAIL PROTECTED]>
>To: "Multiple recipients of list witango-talk" <[EMAIL PROTECTED]>
>Sent: Tuesday, July 23, 2002 10:18 AM
>Subject: RE: Witango-Talk: Caching Problems in General ... was IE caching
>problem
>
>
> > Another thought, regarding this...
> > Have unique URLS won't stop IE's aggressive caching of images though. A
>lot
> > of my caching problems are not the HTML code but images that are cached
>by IE.
> >
> > For example, a recent problem which still has me stumped is the case of
>an
> > admin system which includes a file upload process.
> >
> > The process entails a particular file being uploaded (say emu.jpg) and
>then
> > referenced by the following page (ie ubuys/emu.jpg) to display that the
> > image was successfully loaded. However, if the image changes, though the
> > reference stays the same, the old image will still show, or if there now
>is
> > no image, IE still shows that there is an image. Accordingly the admin
> > system is now "lying" to the administrators and they don't know what to
> > believe.
> >
> > Any ideas on how to get around this?
> > Garth
> >
> > At 11:25 22/07/02 -0700, you wrote:
> > >Good point, Robert .... always thinking ..
> > >
> > >Ian
> > >
> > >-----Original Message-----
> > >From: Robert Shubert
> > >
> > >Just an interesting note:
> > >
> > >The HASH function of T2K restricts output to 32 characters and it is
> > >therefore possible to create two identical HASHes with <@CIPHER
> > >action=hash str=<@CURRENTTIME>>.
> > >
> > >Another way of creating an ever increasing value is <@TSTOSECS
> > ><@CURRENTTIMESTAMP>><@TIMER> This value is ensured to be unique unless
> > >the same person is able to retrieve two pages in the same millisecond.
> > >Keep in mind that this only works if the CURRENTTIMESTAMP is ever
> > >increasing, if you adjust the time on the server (or adjust for daylight
> > >savings) it could create duplication, although it's still highly
> > >unlikely.
> > >
> > >Bob Shubert
> > >Tronics
> > >
> > > > Ian Daniel wrote:
> > > >
> > > > Hey Garth:
> > > >
> > > > We experienced great caching issues which would not all be solved
> > > > using the approach described below. Remember that cache involves
> > > > multiple versions and schemes of browsers, proxy servers, firewalls,
> > > > network routers and servers.
> > > >
> > > > In my experience, the only way to "beat them all" in one action is to
> > > > ensure that every URL is unique.
> > > >
> > > > For dynamically-generated pages, we append what we call a "no-cache"
> > > > argument to every URL. At NCOL, we have standardized on a hash of
>the
> > > > currenttimestamp, like so:
> > > >
> > > > &_nc=<@CIPHER action=hash str=<@CURRENTTIME>>
> > > >
> > > > For statically-generated pages, we add a large random number,
> > > > generated in JavaScript, to ensure that every browser display (even
> > > > those presented by the browser back button) has a unique URL. There
> > > > are several ways to do this. We usually use:
> > > >
> > > > <script language="javascript">document.write('<a href="whatever.taf?'
> > > > + Math.round(Math.random()*1000000000) + '">Your Link
> > > > Here</a>')</script>
> > >
> > >________________________________________________________________________
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>
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