Re: no_cache pragma/cache-control headers : confusion
Hello, KOFrom the code in Apache.xs, it seems like setting $r-no_cache(0) will KOunset the flag, but not remove the headers. Well, the Expires header is also removed. But it's still broken; you can verify this buggy behavior with this simple script: use Apache (); my $r = Apache-request; $r-no_cache(1); $r-no_cache(0); $r-send_http_header; With mod_perls 1.24_01 and 1.25 on Apaches 1.3.14 and 1.3.19, this call leaves me with Pragma and Cache-Control headers. Sadly, the nice (but broken as per above) no_cache() behavior of sending those two headers is also undocumented in the mod_perl guide to begin with. Humbly, Andrew -- Andrew Ho http://www.tellme.com/ [EMAIL PROTECTED] Engineer [EMAIL PROTECTED] Voice 650-930-9062 Tellme Networks, Inc. 1-800-555-TELLFax 650-930-9101 --
no_cache pragma/cache-control headers : confusion
Dear all, There is some kind of confusion in my head, and the Eagle book seems to me even more confusing. Any help appreciated. First, I always thought that no_cache() does everything regarding headers, and that you have just to turn it on or off. However I discovered yesterday that, at least in my setup, even with no_cache(0) I have Pragma: no-cache Cache-control: no-cache which seems counter-intuitive to me. I've checked the Eagle : it says that no_cache() only adds an Expires field. Ok. But then from where does the Pragma header come ? About -headers_out() it is specifically said : In addition, the Pragma: no-cache idiom, used to tell browsers not to cache the document, should be set indirectly using the no_cache() method. So, that seems confusing to me, since the no_cache() methods seem not to deal with Pragma headers. Who sets Pragma/Cache-control headers and why are they like that by default ? How to override that (with headers_out ?) ? TIA. -- Patrick. ``C'est un monde qui n'a pas les moyens de ne plus avoir mal.''
RE: no_cache pragma/cache-control headers : confusion
Apache (as in httpd) will set the 'Expires' header to the same value as the 'Date' header when no_cache is flagged in the request_rec. When your Perl handler sets $r-no_cache(1), mod_perl (in Apache.xs) is setting the 'Pragma: no-cache' and 'Cache-control: no-cache' headers in addition to setting the no_cache flag in the request_rec. From the code in Apache.xs, it seems like setting $r-no_cache(0) will unset the flag, but not remove the headers. -- Kyle Oppenheim Tellme Networks, Inc. http://www.tellme.com -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Patrick Sent: Wednesday, April 04, 2001 2:47 AM To: [EMAIL PROTECTED] Subject: no_cache pragma/cache-control headers : confusion Dear all, There is some kind of confusion in my head, and the Eagle book seems to me even more confusing. Any help appreciated. First, I always thought that no_cache() does everything regarding headers, and that you have just to turn it on or off. However I discovered yesterday that, at least in my setup, even with no_cache(0) I have Pragma: no-cache Cache-control: no-cache which seems counter-intuitive to me. I've checked the Eagle : it says that no_cache() only adds an Expires field. Ok. But then from where does the Pragma header come ? About -headers_out() it is specifically said : In addition, the Pragma: no-cache idiom, used to tell browsers not to cache the document, should be set indirectly using the no_cache() method. So, that seems confusing to me, since the no_cache() methods seem not to deal with Pragma headers. Who sets Pragma/Cache-control headers and why are they like that by default ? How to override that (with headers_out ?) ? TIA. -- Patrick. ``C'est un monde qui n'a pas les moyens de ne plus avoir mal.''
Cache control
I have written a handler for delivering select images for a particular class of URIs based upon a database item that the user sets in advance. This allows us to "skin" some HTML allowing the user to select their look of choice. The problem I have is that IE5 (and perhaps other browsers and versions) but NOT Netscape 4.x have absolutely no respect for cache-control. My code does this: $r-no_cache(1); # some code to calculate a date 10 years ago (!) goes here... $r-header_out( 'Expires' = "$day_text, $day $mon_text $year $hour:$min:$sec GMT" ); $r-send_http_header($subreq-content_type); And the HTTP headers via Lynx look like this: HTTP/1.0 200 OK Date: Fri, 26 May 2000 08:58:38 GMT Server: Apache/1.3.12 (Unix) mod_perl/1.23 Pragma: no-cache Cache-control: no-cache Expires: Tue, 29 May 1990 1:58:38 GMT Content-length: 1332 Content-Type: image/gif But IE5 still caches the damn things! Does anyone have a suggestion? Please note that I don't have the ability to modify the IMG SRC dynamically since the HTML resides on our customers' servers. -- -- Tom Mornini -- InfoMania Printing and Prepress
RE: Cache control
The problem I have is that IE5 (and perhaps other browsers and versions) but NOT Netscape 4.x have absolutely no respect for cache-control. IE5 can be set up to ignore any cache directives and keep a document for either the duration of the session or forever. (Or reload it every single time or check if it should be reloaded...) This might be the cause of its respectlessness :-) -- Eric Jain
[OT] Re: Cache control
Tom Mornini wrote: I have written a handler for delivering select images for a particular class of URIs based upon a database item that the user sets in advance. This allows us to "skin" some HTML allowing the user to select their look of choice. The problem I have is that IE5 (and perhaps other browsers and versions) but NOT Netscape 4.x have absolutely no respect for cache-control. But IE5 still caches the damn things! Does anyone have a suggestion? Please note that I don't have the ability to modify the IMG SRC dynamically since the HTML resides on our customers' servers. I don't yet have a suggestion, but I have the same problem with IE. I'm building a web-based admin section, and IE keeps caching everything. One more reason to hate IE - on IE 5 Mac they changed the default resolution to 96 dpi (up from the std 72 dpi). So now all our style sheets for the mac side have to be tweaked, and I have a lot of code to rework to send the proper stylesheet! Microsoft seems to be very partial to standards - CSS1 is completely implemented in IE5 mac, but it still caches dynamic content! Anyway, sorry for the OT post. I just had to vent... :-) -- Drew Taylor Vialogix Communications, Inc. 501 N. College Street Charlotte, NC 28202 704 370 0550 http://www.vialogix.com/
Re: Cache control
In our experience the only thing that guarantees no cacheing is returning 302. Also appending a query string (even an empty one) to the redirect URI seems to make it even more solid. So in your script you would build up your destination URI, append '?foo=bar' to the end of it, and return it as a redirect. That way not even MSIE will cache it. HTH, Nick On Fri, 26 May 2000, Tom Mornini wrote: I have written a handler for delivering select images for a particular class of URIs based upon a database item that the user sets in advance. This allows us to "skin" some HTML allowing the user to select their look of choice. The problem I have is that IE5 (and perhaps other browsers and versions) but NOT Netscape 4.x have absolutely no respect for cache-control. My code does this: $r-no_cache(1); # some code to calculate a date 10 years ago (!) goes here... $r-header_out( 'Expires' = "$day_text, $day $mon_text $year $hour:$min:$sec GMT" ); $r-send_http_header($subreq-content_type); And the HTTP headers via Lynx look like this: HTTP/1.0 200 OK Date: Fri, 26 May 2000 08:58:38 GMT Server: Apache/1.3.12 (Unix) mod_perl/1.23 Pragma: no-cache Cache-control: no-cache Expires: Tue, 29 May 1990 1:58:38 GMT Content-length: 1332 Content-Type: image/gif But IE5 still caches the damn things! Does anyone have a suggestion? Please note that I don't have the ability to modify the IMG SRC dynamically since the HTML resides on our customers' servers. -- -- Tom Mornini -- InfoMania Printing and Prepress - nick
Re: Cache control
On Fri, 26 May 2000, Nick Tonkin wrote: In our experience the only thing that guarantees no cacheing is returning 302. Also appending a query string (even an empty one) to the redirect URI seems to make it even more solid. So in your script you would build up your destination URI, append '?foo=bar' to the end of it, and return it as a redirect. That way not even MSIE will cache it. Though you walk the Earth, you may indeed be a God! Thank you very much. I wish I would have thought of this myself. -- -- Tom Mornini -- InfoMania Printing and Prepress
