Mike Raiford wrote:
> BTW, why does it seem like the nesgroups site is always so painfully slow?

There are two possible patterns you see, both related to the same technical 
measure:

1. First, the initial view after a few minutes of inactivity (or visiting 
for the first time in a new session) is slow.

The web interface is designed such that is prevents anybody from easily 
making a full snapshot of the whole page against our wishes.  Google is an 
exception, but they obey no-cache and no-index options the website tells 
them about, which most "web mirror" programs do not.

Either way, the trick we use to protect the website from massive downloads 
is that with each access you get a cookie set that contains a counter of the 
number (and just that, we don't track the pages or anything like that) of 
page views in the last several minutes as well as the current time. The 
counter and time are validated with a hash key so it cannot easily be 
manipulated by someone just editing their cookies.  This also makes it 
harder for someone to simply send a non-modifiable cookie, as the time is 
part of the key.

Now, when you access the page for the first time after several minutes, the 
server gets a cookie and notices that its time is too old.  So what it does 
is to simply wait and do nothing for a few seconds (ten iirc) before it 
sends you the first page.  Cookies are updated in your browser with every 
page view, so when you navigate the page actively, you can do so quickly 
without the delay (unless you hit something like more than 20 or so pages 
per minute, but I don't recall the exact limit we set).

2. The view is always slow with every access.

However, if you disabled cookies for the povray.org website in your browser, 
the server will never get a cookie and impose the delay with each access. 
By default the cookies as sent by povray.org to your browser should be 
accepted with the default settings of any browser, but if you use maximum 
security settings (depending on your browser), they might be rejected 
automatically by your browser on your behalf.  In that case you need to 
change your browser setting to allow cookies from povray.org if you want a 
fast site.


In summary, it is not something just you see but that we impose on every 
user in order to protect the contents of this server as good as possible to 
prevent misuse of the message contents.

	Thorsten

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