How do you force browsers to revalidate static content like an swf, xml, txt, … files? We often have this problem with customers and advise them to clear their cache. Not a very good solution don’t you think?
So how do you solve this? We could append the version of our product to the static files, so that with a new release, browsers wouldn’t hit their cache loading the file. A condition for this to work would be that the home page (default page) should always be the latest version from the server. This page would have references to the static files with version appended to them.
What about browsers asking the server if a newer version is available. In comes the must-revalidate header.