Meta Tag for Cache issues

Any speed implications ?

[stuart]

I'm looking to use the following meta tag so regular visitors always get the latest info. I am wondering if this tag is going to slow things down or present any other problems, I use 30 small gifs on each page (20 are copied from 2) and 10 small jpegs. TIA.

<meta http-equiv="Pragma" content="no-cache">
<meta http-equiv="Cache-Control" content="no-store,max-age=-1">

[GWJ]

The disadvantage would be regulars have to wait for the page and images to come back down to cache each time. Guess in my mind it would depend on how long does the page take to download? If it is a fast load then I know I would not mind as an end user/surfer.

Brian

[gmiller]

The meta elements should not affect any images or other objects referenced from the page, only the page itself.

[tedster]

There's some very spotty and conflicting information on the web about MSIE and the Pragma meta tag. Some pages state flat out that IE does not support the Pragma tag, but this seems to be only a partial story.

Here are two articles from Microsoft:

Pragma Tag May Not Prevent Page From Being Cached [support.microsoft.com]

How To Prevent Caching In Internet Explorer [support.microsoft.com]

I've been confounded looking for Netscape documentation. I have found some sites that claim the pragma meta WILL stop image caching, and they claim a 15% increase in banner ad impressions by using it. They say that the tag means a new impression, even on Back button page views. They also caution that invalid cache control tags can stop a page from being displayed at all.

gmiller,
you've given nothing but good solid info on the forum, and I'm inclined to believe you on this issue. Do you have reference handy on the pragma tag and image caching?

[GWJ]

Thanks for the correction gmiller. Mentaly noted.

Brian

[gmiller]

Well, the one catch is that word "should"... http-equiv meta elements are supposed to function the same way as real HTTP headers, and the HTTP spec (IETF RFC 2068 is the current one) says that it indicates that the current response should not be cached. Any images or applets are retrieved by a separate response after the HTML has been parsed, and get their own caching parameters. That's why banner ad companies are able to send a different ad every time you view a page, even if the page is cached.

But that only describes how things work when the client and proxies do what they're supposed to. I haven't noticed any doing the wrong thing with regard to images, but I wouldn't be surprised if they got it wrong under some circumstances. NS6 and Mozilla don't cache POST data and MSIE has the quirks mentioned in those MS support articles mentioned above, so one more caching bug wouldn't knock me out of my chair ;)

[Brett_Tabke]

The way I understand it, only IE 4 uses the Meta tag no-cache tags. Opera 5 did in early .01 builds, but screaming from users got it changed in .02. The blurb about pragma no-chace in the 1.1 rfc was related to http headers - not meta tags.