So the first issue is that they have too many users for their
bandwidth, second is they either cannot afford the cost or the
additional bandwidth is not available to them.
Then to complicate the issue a little more you add on my software
being browser based and there are a lot of graphics loaded to the
browser...
These are circumstances where using a proxy on the customer's side may
be a good idea.
Another question is whether the customers should not use a proxy anyway
for all their traffic.
If you want to cache mainly image content, this can be done by any HTTP
proxy without special configuration.
What do you mean by "the link inside the app would be dynamically
generated with the page"?
If the filename of the graphics file remains the same, the proxy will
serve it from its cache when it is requested,
no matter if the request comes from a dynamically generated page
[provided that the cache-control and expiry settings allow caching].
If your graphics files are referenced by different filenames each time
(which may be mapped to the same content by the application), the proxy
has no way to know that it is actually the same content and will request
the "new" file from the server.
As for browsers and caching, there are tutorials out there that can tell
you hot to set the cache-control and expiry headers so that you achieve
what you want. I would estimate 90% of the HTTP servers just run "as-is"
in this respect which means that they determine expiry itself.
See e.g.
http://developer.yahoo.com/performance/rules.html
HTH,
Jakob Curdes
