Let's say we have an HTTP server that handles two URLs: http://server/foo and http://server/bar. And let's say we have only one HTTP agent ever hitting those URLs.
The server will add distant-future cache headers on requests to /foo because, most of the time, this resource will be the same for the foreseeable future and it would make sense for agents to cache it.
Well, it's actually really the same until the agent hits /bar. At this point the /foo resource should be re-fetched because the cached version is most likely not up-to-date.
So can the server, when handling a request for /bar, also indicate the HTTP agent that any cached version of /foo should be discarded and re-fetched if needed?