"Hits" pragma

Paul Burchard (burchard@horizon.cs.princeton.edu)
Fri, 11 Aug 95 23:05:35 -0400

Brian Behlendorf <brian@organic.com> writes:
> One thing that would encourage the use of Expires:
> headers of course would be a way for caches to report hits
> they served directly without a long-distance conditional GET.

How about using an additional pragma directive

Pragma: hits = 35

to denote the accumulated number of unforwarded requests received
by a proxy, in addition to the request being forwarded. Multiple
"hits" directives make sense, and can be accumulated by intermediate

Using this pragma, hit counts will be accurate over time intervals
on the order of the expiration interval of the resource (which is
tunable by the server).

This proposal requires only minimal changes to caches, servers, and
log analysis tools -- and offers a graceful, incremental upgrade
path in the meantime (since Pragma headers are already passed
through by any conforming proxy). Performance of all components is
practically unchanged since no additional network connections are
used. And perhaps most important for successful adoption, this
scheme avoids imposing any burdensome reporting duties (such as
"accounting batch runs") on proxy maintainers.

Paul Burchard <burchard@cs.princeton.edu>
``I'm still learning how to count backwards from infinity...''