Last-Modified Header Not Added to JS/CSS Files

[GoogleCodeExporter]

What version of Minify are you using? PHP version? 2.0.1

What steps will reproduce the problem?
1. Clear browser cache
2. request JS or CSS files generated by Minify
3. note that there is no Last-Modified header on the file

What is the expected output? What do you see instead?
I'm expecting to see a "304 Not Modified" response when requesting the same
CSS or JS file in subsequent requests.  As background, in FF and IE at
least future requests will not include an If-Modified-Since header unless
there was a Last-Modified header included in a previous response.  As a
result my browser is requesting and downloading the JS/CSS files on every
page request.

Please provide any additional information below.
If this is not the intended behavior, I noticed that the constructor for
HTTP/ConditionalGet.php is returning before checking for the
'lastModifiedTime' array element in the $spec variable passed to it.  It's
the presence of this variable that will trigger the Last-Modified header. 
From what I can see this code simply never executes.  See snippet below.

        if (isset($spec['setExpires'])) {
            if (is_numeric($spec['setExpires'])) {
                $spec['setExpires'] = self::gmtDate($spec['setExpires']);
            }
            $this->_headers = array(
                'Cache-Control' => $scope
                ,'Expires' => $spec['setExpires']
            );
            $this->cacheIsValid = false;
            return;
        }
        if (isset($spec['lastModifiedTime'])) {
            // base both headers on time
            $this->_setLastModified($spec['lastModifiedTime']);
            $this->_setEtag($spec['lastModifiedTime'], $scope);

Original issue reported on code.google.com by vadib...@gmail.com on 16 Jul 2008 at 11:21

[GoogleCodeExporter]

Are you using the 'setExpires' option in serve()?

When using 'setExpires', Last-Modified and the check for If-Modified-Since are 
not 
needed. After the Expires header is sent, under normal browsing the browser 
will not 
re-request the file at all until the expiration time.

Only when you explicitly request the JS/CSS URL or refresh the HTML page will 
the 
browser re-request the file, and when it does it will not send a conditional 
GET, so 
Last-Modified would be a waste.

You can verify this using Fiddler and navigating around on http://
www.miamianimalremoval.com/ (uses 'setExpires'). The /min/ URLs are not 
re-requested 
unless you manually refresh a page, and when you do, IE7 sends Pragma: 
no-cache, so 
it wouldn't send an If-Modified-Since header anyway.

If you want conditional GETs and 304 responses, don't use the 'setExpires' 
option.

Original comment by mrclay....@gmail.com on 17 Jul 2008 at 6:06

• Changed state: NeedInfo

[GoogleCodeExporter]

After further testing and reading the code I realized this was probably the 
issue. 
Still, I'm not sure I agree with your statement that on refreshing the page the
browser won't do a conditional get.  In my FF2 and IE7 browsers I can see the
If-Modified-Since headers being sent for image requests that had a Last-Modified
header on a previous request.  It seems even if there is even partial support 
for
this in browsers having the Last-Modified in there could save some round-trips 
with
no adverse affects.

In either case, that would be in the realm of a feature request so I assume you 
can
just close out this erroneous bug report.  Thanks and sorry for the confusion.

Original comment by vadib...@gmail.com on 17 Jul 2008 at 6:23

[GoogleCodeExporter]

So the requested feature would be: When 'setExpires' is used, Minify should 
still 
support conditional GETs?

My reasoning for not supporting conditional GET in this case is that it speeds 
up 
Minify by not loading ConditionalGet.php at all (in 2.0.2b).

My intuition is that, when far-off Expires headers are used, conditional GET 
requests are pretty rare, but I guess some testing is in order. If you have 
pages 
that invite refresh-a-thons (eBay bidding) and conditional GETs are sent, 
there'd be 
a lot of opportunity for bandwidth savings.

Original comment by mrclay....@gmail.com on 17 Jul 2008 at 9:00

[GoogleCodeExporter]

Exactly.  I'm also wondering about pages with a meta-refresh (not sure what the
behavior is here but I'd bet it acts like a manual refresh) or AJAX-refreshed 
pages,
which are more and more common.

Original comment by vadib...@gmail.com on 17 Jul 2008 at 9:23

[GoogleCodeExporter]

[deleted comment]

[GoogleCodeExporter]

Created feature request:
http://code.google.com/p/minify/issues/detail?id=37

Invalidating this issue.

Original comment by mrclay....@gmail.com on 17 Jul 2008 at 11:09

[GoogleCodeExporter]

I don't know why I made a separate issue for this.

Original comment by mrclay....@gmail.com on 27 Nov 2008 at 3:45

• Changed state: Verified