Don't worry about your English--it may not be gramatically
perfect in every detail, but it's certainly understandable!
So, definetly it is not possible with Apache and PHP to take
out this inoformation ?
I wouldn't put it that way. A better description is to say that
this information is inherently not available due to the nature
of http. If ASP provides a built-in way to approximate it, then
all it means is that someone there decided on one particular
way of presenting a fake "users-on-the-site" count, and you
are at the mercy of their determination of what's reasonable.
This is why I said, if you're determined you must do this, at
least by rolling your own you will get to decide how to do it,
and balance the tradeoffs involved to your own liking.
For starters, there is no such thing as an http session that extends
over a single page view. (Yes, you can use keep-alive, but just
like pconnects in php, it's merely a performance enhancement,
and does nothing to provide any continuing state information
from one page to the next.) So, if you're not using sessions,
whether built-in, phplib, or your own system, there is no way
to determine that successive page views are from the same "user".
People sometimes try to do this using ip addresses, but there
is not (and never has been) a one-to-one correspondence between
individual browsers and ip addresses. And since there's no state,
then there's inherently no indication that the user is no longer
"on" your site. The only way to determine this is to log the ip
address and a timestamp, and then decide how long before you
count that address as lo longer "there".
With sessions, at least have a moderately reliable way of knowing
when someone logs in, but logging out is completely optional, so you
are again left with determining some kind of average decay time before
you consider the user gone, even if they haven't logged out.
