If you only want the output, and www.asite.com is PHP-enabled,
then you can use fopen() to read the data and print it in your script.
If www.asite.com is not PHP-enabled, and you still fel brave enough to run a script that's on that server on your site, you can just use include like with any other php script:
http://www.php.net/manual/en/function.include.php
But remember that including php-scripts from other servers is a bit like playing the solitaire version of russian roulette.