Check if a remote www-page is online...

Hi,

I have a PHP-page that fetches information from another site, BUT the problem is that the site sometimes is not available or extremely slow. Hence, I would like to check if the site is online, prior to fetching the information from the site. How do I do that in the best way?

I have tried to use both
fsockopen("www.example.com",80);
and
file_get_contents()

Is there someway to set a timeout-limit?

Thanks in advance,
Jan