real time info to web browser from apache side ?

[Larry Bates]

Joseph wrote:
> 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
> 
I would use AJAX so that I could query the server via XMLrpc
calls to update the browser.  You can have much higher refresh
rates using this method.  The alternative is to just have
the browser refresh every few seconds by imbedding a header at
the top.  Something like:

<meta http-equiv="refresh" content="10">

Refresh every 10 seconds.

-Larry Bates

would refresh every 10 seconds.