W3C home > Mailing lists > Public > ietf-http-wg-old@w3.org > September to December 1996

Re: Hit-metering: to Proposed Standard?

From: Jeffrey Mogul <mogul@pa.dec.com>
Date: Tue, 26 Nov 96 11:26:27 PST
Message-Id: <9611261926.AA06441@acetes.pa.dec.com>
To: hardie@nasa.gov
Cc: http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
    >The "stickiness" of the Meter request-directive is only a
    >performance optimization, and if there are serious technical
    >arguments against it, we could remove that without affecting any
    >other aspect of the proposal.

    >But I do not think it is accurate to think of this in the same way
    >that we have previously discussed "sticky" headers, since those
    >were for actual request-headers.  The Meter request header is a
    >sort of unusual thing that applies to transport-level connections,
    >not to individual requests, and so it might probably be better to
    >use a term other than "sticky" here.  (The Meter response
    >directives are per-response, but hop-by-hop, and so if there is a
    >general "sticky" mechanism agreed upon for the rest of HTTP, then
    >it could take advantage of this.)

   I'm not sure how good an optimization it is.  You mentioned above
   that an server would probably cache-bust now only on those
   resources for which it needs accurate counts (like an ad image).
   By making this a per-connection header, you seem to me to force a
   proxy to report and a server to receive information it may well
   throw away (like the counts on every little fancy bar or button
   image).

I don't think my original response was clear enough. The Meter
response directives are NOT STICKY; to quote from the I-D:

   The Meter response-directives are not sticky; they apply only to the
   specific response that they are attached to.

This means that we are not "forcing" a server ask for information
that it will throw away; it must explicitly request Metering for
each response individually.  We certainly do not expect (or want)
origin servers to hit-meter those bars and buttons!

There is a somewhat confusing situation, which may not have been
helped by one of the examples in the I-D, which is that one
can omit the "Meter" header on the *first* (and only the first)
response on a connection, because the "Connection: meter" header
that must be sent if one is doing Metering has (by the HTTP/1.1
spec) the implication that the Meter header is present in that
response.  Maybe this example needs some more explanation in the text.

-Jeff
Received on Tuesday, 26 November 1996 11:44:48 EST

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