Re: Expiring other resources with HTTP headers

I don't think you can expire another file, I would consider any ability to do so a bug in the browser. Someone with too much time on their hands could possibly turn something like that into a security risk. I would solve the changing javascript problem by subtly altering the pages that use the javascript file. A web browser will recognise menu.js, menu.js?ver=1 and menu.js?ver=2 as different pages. You can use this for your application by including menu.js?ver=$ver in each of your pages. When the menu is modified and regenerated, increment $ver. Every client will refetch menu.js as it views it as a different file. David William Lovaton wrote: > Hello everybody, > > I write here to find out if this is possible: > > I want to expire an static file in the web browser through an HTTP > header (Expires, Cache-Control or something else) sent from a PHP > program. The usual thing is that those headers apply only to the > program or file sending those headers, what I want is that a program > sends those headers to affect a different file in the browser cache. > > In more detail, My web app generates a JavaScript file from the > information stored in the database, that file represents the user menu > and it is what the user sees in the web browser. Now, through an apache > directive I set expiration times for several kinds of static resources > so the web server doesn't get slash dotted with lots of unnecessary > requests (this is a web app with lots of traffic). > > Although the JavaScript files are generated from PHP, it is seen as > static content from the web browser POV. Right now I have set the > expiration time for the menu files to 20 minutes. But let's say an > admin user change the permissions of a user and the affected user hits a > link that says "Regenerate menu". What will happen is that the > JavaScript file will be regenerated on the web server but there is a > chance that the browser won't see the change because the file is still > valid in the cache. > > I know I could reduce the expiration time to reduce this problem but > most of the time those files do not change. What can I do to notify the > web browser that the file in the cache is no longer valid? > > I hope there is enough information here and that somebody can give me a > hint in the right direction. > > Thanks, > > -William >