real time info to web browser from apache side ?

[Joseph]

I know about writing CGI application using Perl and Apache to refresh a
static webpage that displays on the browser.  But now i have an
application requirement that I hope someone can help me.

The server side sits in another room down the factory plant, its
monitoring some hardware environment, namely temperatures and pressures
etc inside the plant.  This server of course have Apache running.  I
would like to be able to have a browser in the comfortable office
somewhere point to the apache server, and after I enter the password,
it would display the temperature and pressures etc in the plant (in
real time, ie. as the temperate changes from a degree to another, the
browser will immediately display this).  So I am looking more for a
push technology than a pull from teh browser (user hit Ctrl-R to
refresh is a pull).

What are the current technology that allows for this.  I know its
possible because I can use my browser sometimes to chat with people
online, and I swear that I don't have to do a Control-R everytime to
see that the other person's typing is updating constantly on my
browser.

Thanks in advance,
Push technology wannabe