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GollyJer
Asked: 2011-04-07 12:54:36 +0800 CST

Is there a way to turn off client browser caching for specific websites?

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This is a browser agnostic question but we're testing with IE9.

One of the web apps our users visit is being randomly cached and changes aren't showing up when they should. No other site has this issue and we've worked with the vendor who claims it isn't happening to anyone else. If we use the developer toolbar and select "force refresh from server" everything updates correctly.

Instead of truly solving the issue our thought is to work around it by disabling cache for this specific site. However, we don't know how.

http cache internet-explorer web-server

5 Answers

  1. Best Answer

    The only proper way of disabling browser caching is by HTTP headers from the webapp itself. The HTTP 1.1 "Cache-Control" header alone should suffice for any post-year-2000 browser. But for extra protection the server can emit both HTTP 1.1 "Cache-Control" and HTTP 1.0 "Expires" headers together.

    A hack'ish but sometimes seen way of handling cache invalidation is a "cachebuster" string in URLs from the server. The cachebuster is often timestamp based, and is added as a querystring to each HTML LINK to make the URL unique and only used once. Something like http://example.org/filename.html?cb=<timestamp+random_value>. This is ugly, and doesn't do anything the HTTP headers don't do far better. But it could be used as a hack for a limited audience (fx on an Intranet), or as an additional layer of protection together with proper HTTP headers.

    AFAIK there is no way to selectively disable caching for a single site only from within Internet Explorer. One (bloody complicated) solution could be to install Varnish cache as an intermediary cache on your LAN, set Internet Explorer to use Varnish as HTTP proxy, and use the VCL language on Varnish to re-write the HTTP headers for this specific site only.

    Honestly, I think your vendor is making a mistake here. I would suggest to install Fiddler2 for IE, or Firebug for Firefox, and look at the actual HTTP headers the webapp sends. Correlate that with Mark Nottingham's caching tutorial which I already linked to above -- I'm guessing the headers permit caching, or at least don't expressively forbid caching.

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  2. Make sure you set the proper expire headers. If you put the time in past, the content will not be cached. Check the time/date on the workstation where IS9 runs. See also: http://www.mnot.net/cache_docs/

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  3. If you cannot modify the contents of the web site in question, you can use a proxy server to modify the content enroute to your browser. This would allow you to change the expire headers.

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  4. If the website allows you to connect via HTTPS, then depending on your browser, you can disable caching encrypted pages.

    In IE, this can be done thusly:

    You can double check IE's settings in Internet Options->Advanced->Security->Do not save encrypted pages to disk.

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  5. <meta http-equiv="PRAGMA" content="NO-CACHE">

    http://www.zann-marketing.com/developer/20051018/stop-browser-caching-using-meta-tags.html

    You may wish to consider using random keys in the URL bar, this will also prevent caching within the browser.

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