Flickr Sends Goofy HTTP Headers- Philip Jacob

Flickr is sending the following HTTP headers when I request an image from their site (http://static.flickr.com/25/45701618_b33d84770b_s.jpg):

GET /25/45701618_b33d84770b_s.jpg HTTP/1.1
Host: static.flickr.com
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.10) Gecko/20050716 Firefox/1.0.6
Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
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
Cookie: cookie_epass=9df5184c71b811e5bf1081de83e24d51; cookie_accid=16665; cookie_session=16665%3A9df5184c71b811e5bf1081de83e24d51; use_master_until=1127567132
Pragma: no-cache
Cache-Control: no-cache

HTTP/1.x 200 OK
Date: Fri, 23 Sep 2005 01:13:26 GMT
Server: Apache/2.0.52 (Red Hat)
Last-Modified: Fri, 23 Sep 2005 01:13:23 GMT
Etag: "91e011-d08-1dacd2c0"
Accept-Ranges: bytes
Content-Length: 3336
Content-Type: image/jpeg
X-Cache: HIT from storage7.flickr.mud.yahoo.com
Connection: close

This is completely valid HTTP, but I really wish they were sending back a proper Expires header like this:

Expires: Mon, 24 Oct 2005 15:12:45 GMT

If they sent back this HTTP header, my browser wouldn’t have to perform conditional-GET requests for subsequent loads of images on Flickr. The part of the HTTP request that makes the GET conditional is highlighted below:

GET /25/45701618_b33d84770b_s.jpg HTTP/1.1
Host: static.flickr.com
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.10) Gecko/20050716 Firefox/1.0.6
Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
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
Cookie: cookie_epass=9df5184c71b811e5bf1081de83e24d51; cookie_accid=16665; cookie_session=16665%3A9df5184c71b811e5bf1081de83e24d51; use_master_until=1127567132
If-Modified-Since: Fri, 23 Sep 2005 01:13:23 GMT
If-None-Match: "91e011-d08-1dacd2c0"
Cache-Control: max-age=0

HTTP/1.x 304 Not Modified
Date: Sat, 24 Sep 2005 15:19:32 GMT
Server: Apache/2.0.52 (Red Hat)
Etag: "91e011-d08-1dacd2c0"
X-Cache: MISS from storage7.flickr.mud.yahoo.com
Connection: close

Instead, my browser would notice that it has been told not to request this resource until Oct 24th, which is exactly one month from today and would display the image from the local browser cache. There wouldn’t be any network overhead at all and Flickr images would be served a lot faster.

I don’t see what the point of only allowing conditional GET requests is. Flickr isn’t benefitting anybody by doing this. Failing to use Expires: headers for static content only serves to slow down the user experience and increase load on their systems.

Sysadmins at Flickr: read the mod_expires documentation and switch this thing on.