Caching issues and unnecessary browser requests that would trigger a 304 respon

[ramow]

I am trying to optimize the delivery of my javascript files. I am

using the "Header" mod_header directive in the httpf.conf:

 

Header add Expires "Mon, 28 Jul 2014 23:30:00 GMT" env=VERSIONED_FILE

Header add Cache-Control "max-age=315360000" env=VERSIONED_FILE

 

As you can see, I am setting the expires and Cache-Control in order to

make sure that the browser won't ask for the file again. I am using

Firefox.

 

Summary: the first time the browser get the file my server sends back

the special infinity Expires/Cache-Control. in the header BUT my

Firefox always request the file again with a soft refresh. The time to

send another request and get a 304 code back is a wasted precious

time. How can I solve this problem? Ultimately I want the browser to

respect the Expiry date and cache control I have set.

 

I know that not all browser respect those value but as long as IE and

Firefox are concerned they do respect that by their default settings.

SO WHAT's HAPPENING HERE???!?

 

Please help!!!

 

--Rami

 

Here is the firebug output:

 

#1:

--------------------------------------------------------------------------------------------------

HTTP/1.0 200 OK

--------------------------------------------------------------------------------------------------

Response Headers

Date    Fri, 21 Nov 2008 02:50:33 GMT

Server  Apache

Last-Modified  Wed, 19 Nov 2008 04:59:15 GMT

Etag    "9e8436-3f9-45c03ac774ec0"

Accept-Ranges  bytes

Content-Length  1017

Expires Mon, 28 Jul 2014 23:30:00 GMT

Cache-Control  max-age=315360000

Keep-Alive      timeout=15, max=100

Connection      Keep-Alive

Content-Type    application/x-javascript

 

Request Headers

Host    ##############

User-Agent      Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.4)

Gecko/2008102920 Firefox/3.0.4

Accept  text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8

Accept-Language en-us,en;q=0.5

Accept-Encoding gzip,deflate

Accept-Charset  ISO-8859-1,utf-8;q=0.7,*;q=0.7

Keep-Alive      300

Connection      keep-alive

Pragma  no-cache

Cache-Control  no-cache

 

After a soft refresh. (F5 and NOT ctrl+F5)

#2

--------------------------------------------------------------------------------------------------

HTTP/1.0 304 Not Modified

--------------------------------------------------------------------------------------------------

Response Headers

Date    Fri, 21 Nov 2008 03:06:28 GMT

Server  Apache

Last-Modified  Wed, 19 Nov 2008 04:59:15 GMT

Etag    "9e8436-3f9-45c03ac774ec0"

Accept-Ranges  bytes

Content-Length  1017

Expires Mon, 28 Jul 2014 23:30:00 GMT

Cache-Control  max-age=315360000

Content-Type    application/x-javascript

 

Request Headers

Host    ##############

User-Agent      Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.4)

Gecko/2008102920 Firefox/3.0.4

Accept  text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8

Accept-Language en-us,en;q=0.5

Accept-Encoding gzip,deflate

Accept-Charset  ISO-8859-1,utf-8;q=0.7,*;q=0.7

Keep-Alive      300

Connection      keep-alive

If-Modified-Since      Wed, 19 Nov 2008 04:59:15 GMT

If-None-Match  "9e8436-3f9-45c03ac774ec0"

Cache-Control  max-age=0

[kevintynfron]

Hi ramow,

 

I've just been/still going through  the same kind of thing.

 

What I found was that a soft refresh (F5) requests far more things than I expected. Using a navigation link on the web page made things behave as expected.

 

i.e. hitting F5 when viewing the home page requested items with far future expires headers, whereas clicking on a link to the home page and bringing it up that way saw everything behave as I expected, and not request the items with expires headers.

 

I have no idea why, but that's what I saw. See if you get the same.

 

Cheers,

Kevin