Redirect browser to another location and force refresh

I would like to kindly ask you for a suggestion regarding browser cache invalidation.

Let's assume we've got an index page that is returned to the client with http headers:

开发者_如何学JAVA

Cache-Control: public, max-age=31534761
Expires: Fri, 17 Feb 2012 18:22:04 GMT
Last-Modified: Thu, 17 Feb 2011 18:22:04 GMT
Vary: Accept-Encoding

Should the user try to hit that index page again, it is very likely that the browser won't even send a request to the server - it will just present the user with the cached version of the page.

My question is: is it possible to create a web resource (for instance at uri /invalidateIndex) such that when a user hits that resource he is redirected to the index page in a way that forces the browser to invalidate its cache and ask the server for fresh content?

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I'm having similar problems with a project of my own, so I have a few suggestions, if you haven't already found some solution...

1. I've seen this as a way jQuery forces ajax requests not to be cached: it adds a HTTP parameter to the URL with a random value or name, so that each new request has essentialy a different URL and the browser then never uses the cache. You could actually have the /invalidateIndex URI redirect to such a URL. The problem of course is that the browser never actually invalidates the original index URL, and that the browser will always re-request your index.

2. You could of course change the http header Cache-Control with a smaller max-age, say down to an hour, so that the cache is invalidated every hour or so

3. And also, you could use ETags, wherein the cached data have a tag that will be sent with each request, essentially asking the server if the index has changed or not.

2, 3 can be even combined I think...

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There is no direct way of asking a browser to purge its cache of a particular file, but if you have only a few systems like this and plenty of bandwidth, you could try returning large objects on the same protocol, host, and port so that the cache starts evicting old objects. See https://bugzilla.mozilla.org/show_bug.cgi?id=81640 for example.