[Zope] Browser Sticky Fingers

[Jeff Rush]

Hmmm, I'm staring at web sites that -do- update their graphic
content, such as weather display sites and the MRTG (network
graph stats) program, and I don't see anything like a variable URL.

How do they manage it?  The only new item I see is the use of:

<META HTTP-EQUIV="Refresh" CONTENT=300>
<META HTTP-EQUIV="Expires" CONTENT="...a date">

While this would cause the HTML to refreshed periodically,
how are they getting the browser to re-fetch the *images*?
I've captured the HTML source for several iterations and the
<IMG SRC="blah"...> part never changes, so I would expect
the same graphic would keep appearing on each cycle.

-Jeff Rush


On Tue, 19 Oct 1999 09:16:24 +1000, Anthony Baxter wrote:

>Yep. Browsers suck. They cache images regardless. The disgusting 
>hack is to always call your image with the current time in the URL -
>eg. <img src="/your/image/method?dummy_ts=<dtml-var "ZopeTime().timeTime()">">
>/your/image/method should feel entirely free to ignore dummy_ts.
>
>This way the image has a different URL, and so the browser doesn't
>use a cached one.
>
>When you're producing on-the-fly live statistics as a graph, this 
>hideous misfeature is a complete pain in the clacker.