New posts not appearing in threads
I've just been looking a bit more into the issue of recent posts not appearing because the forum pages get cached by ISP proxy servers. Apologies if this gets technical, but there's really no other way to put it. This applies to HWC and VDr equally (and quite possibly SE, although I don't use those forums myself). The basic problem is that someone can post, but when the page is reloaded their post isn't at the bottom. That can last for hours or days depending on the proxy server involved unless the user does Shift-Reload. That gets real boring after the 3rd or 4th thread, especially on a dialup connection. Trust me on that one.
As far as I can see, the only anti-caching method used by the forums is in the form of a no-cache pragma tag at the top of each web page:
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
That does a fine job of preventing browsers from caching the page, but does nothing against proxy servers. Proxy servers may choose to recognise the tag on its way through and not cache the page, but there's no requirement in the standards for them to do so. In fact, some proxy servers (MS Proxy comes to mind) don't even have an option to recognise no-cache tags.
According to RFC2616, the way to force a proxy server to not cache a page is to return no-cache directives in the HTTP header field in addition to the tag in the data itself. That means both "Pragma: no-cache" (section 14.32, for HTTP/1.0 caches) and "Cache-Control: no-cache" (section 14.9, for HTTP/1.1 caches) directives.
Is there any chance the forums servers could be configured to include those directives in the headers they return? I know it's a big ask, but my ISP just reconfigured the one proxy that was listening to no-cache tags and I don't have a leg to stand on against them because the tag is meant for browsers, not proxy servers. Technically, the forums aren't asking for the page to not be cached, and the proxy server is behaving within spec.
I'm not expecting an instant fix, but if you could maybe pass this on to whoever calls the shots with respect to the web servers themselves that'd be great. If there's something in all of that which isn't clear then let me know and I'll attempt to clarify.
[This message has been edited by Tuttle (edited 06-25-2001).]