Tells the browser to cache static files for a long time.
Tells the browser to cache static files for a long time. This works well even when this is a cluster of web servers behind a load balancer because the URL created by urlForResource is in the form: resource?etag
Don't worry that browsers do not pick up new files after you modified them, see the doc about static files.
Google recommends 1 year: http://code.google.com/speed/page-speed/docs/caching.html
Both Max-age and Expires header are set because IEs use Expires, not max-age: http://mrcoles.com/blog/cookies-max-age-vs-expires/
Prevents client cache.
Prevents client cache. Note that "pragma: no-cache" is linked to requests, not responses: http://palizine.plynt.com/issues/2008Jul/cache-control-attributes/