[NNTP] Adding A Quota Command to NNTP (internet-draft)
ade at lovett.com
Thu Feb 22 20:05:46 PST 2007
On Feb 22, 2007, at 18:35 , Samuel Kleiner wrote:
> Would it help to have the byte-quota information timestamped, so
> that the client
> can make predictions based on it?
> In addition, I feel that the slow quota updates of current
> providers have a lot to do
> with the current scarcity of methods to provide accurate and timely
> quota information.
That's not the issue at all. It's a question (as so much of what
makes large-scale Usenet provisioning hard) of scale.
Take a simple situation. Two client threads, connected to
news.example.com, which happens to be an L4 loadbalancer, and the
threads actually end up on completely distinct machines.
Getting the state information in an accurate manner to a potential
request from either thread A or thread B, which has to take into
account in-progress transactions from the other, requires a
considerable amount of extra state information to be thrown around
between the frontend servers and the accounting backend.
Further, since caching of such information is likely to be
undesirable, every request for quota information received by a
frontend has to be sent off to the accounting backends, the records
looked up, and returned, thus also driving transaction rates up.
That's just for a single client, with two threads. Now scale the
situation up to that of a decently-sized commercial Usenet
outsourcer, with tens, possibly hundreds of thousands of active
connections, with 1-N threads for a specific identifiable customer,
and that small amount of extra state information being passed around
rapidly overwhelms the systems.
However, the real deal breaker as I see it is that such an NNTP-based
quota mechanism is only going to work for folks with direct
accounts. Those that get access to Usenet via a corporate outsourced
agreement with an NSP are not going to have that data available to
them. Conveniently ignoring privacy issues for a second, think about
how it would work where the method of authentication is purely IP-
based, where the ISP is handing out DHCP addresses. With only the IP
address to go on, how are quotas handled by the NSP? Does the ISP
(who would be able to map an IP address to a specific customer based
on DHCP lease) have to put in a suitable proxy in order to provide
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