Re: Session tracking

Dave Cardinal (
Tue, 18 Apr 1995 19:00:49 +0500

At 01:28 PM 4/18/95 +0500, David C. Martin wrote:
>I heartily agree; this helps with some problems that I have been
>discussing in terms of tracking a user for providing both dynamic pages
>as well as having dynamic action.
>Now that we have just made HTTP (optionally) stateful, what did we

My vote is that Session-IDs are much more tenable than putting miscellaneous
tokens into the URLs--which cause them to fail later. Those not only
add an implicit state, but they are in effect not "optional" for the
client side, since they are imposed by the server.

>Paul Burchard writes:
>Brian Behlendorf <> writes:
>> "Clickstreams" are the paths people take when they
>> traverse your site - many content providers would find it
>> useful to be able to detect common patterns or the
>> effectiveness of various user interfaces.
>> So, I'd like to propose for discussion a new HTTP header
>> (hi Roy!) called "Session-ID". This would be optional,
>> of course, and it would change any time the browser is
>> restarted (or when the user wished).
>This is an excellent idea. With Referer logging, you can already
>produce a "Markov model" for your Web site, giving transition
>probabilities between pages. But it would be interesting to find
>out just how independent link choices really are; i.e., once a user
>gets to a page, how much does it matter where they came from? To
>the extent that it matters, the Markov model is inaccurate.
>> Given that more than one person can use a hostname (proxy
>> servers, etc), there's no reliable way to exactly identify
>> a unique person without implementing access control
>Yes, and the statistics of access intervals don't help. Intervals
>between requests from the same host seem to follow a combination of
>two very distinct exponential distributions whose decay rates
>differing by over an order of magnitude; presumably the long-term
>exponential represents intervals between user sessions through the
>same gateway host. But the problem with exponential distributions
>is that the maximum probability occurs at zero, no matter how long-
>or short-term they might be...
>Paul Burchard <>
>``I'm still learning how to count backwards from infinity...''

Dave Cardinal
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