I assume that you want a PHP script that processes something and displays it every 45 seconds. Like refreshes itself every 45 seconds automatically.
You may want to look into the PHP sleep() command at http://us4.php.net/manual/en/function.sleep.php
You could process, sleep, process the same thing again, sleep, etc. With this method the script never really ends, unless you end it at some point in the code, or the user moves on to another page or click on a link of yours.
There is another way using redirection, but I'm having a hard time remembering the syntax. With the header() redirection you could tell the script to run itself in 45 seconds. This means that your script really ends each time, but before it does it instructs itself to startup again in 45 seconds.
Don't hold me to it but the syntax is something like this:
header('Location: {45}http://www.example.com/process.php');
I just don't remember where the curly braces are supposed to be in this location field. The value inside the curly braces is the seconds to wait before redirection.
The problem with the header() command is that it must be executed before any output is sent to the browser. So, if you need to display something first, you'll have to buffer your output using ob_start() and ob_end_flush() or discard output using ob_end_clean().
This is of course if you want to do it using PHP.
Look at these PHP commands:
http://us4.php.net/manual/en/function.header.php
http://us4.php.net/manual/en/function.ob-start.php
http://us4.php.net/manual/en/function.ob-end-flush.php
http://us4.php.net/manual/en/function.ob-end-clean.php
