Calling PHP functions from different domains

Is it possible to call a PHP function found in a file on another website with a different domain?

For example, I know that to call a PHP function from another file in the same domain (say function aaa() found in aaa.php) I just have to simply do this (with a few simplifying assumptions):

include_once('aaa.php');
aaa();

I have tried doing something similar, such as:

inclu开发者_如何学运维de_once('http://othersite/aaa.php');
aaa();

I cannot get this to work (the page seems to load fine, with no error messages, but the function does not execute). I have tried require(), which gives me a blank screen. I have had no success with fopen either.

If it is possible to do this, how can I do it?

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The include and require (and their _once variants) take a local filesystem path as their parameter. Domains have nothing to do with it.

Yes, you can also put an URL there (if you have the fopen wrappers enabled), but then PHP will just download the file and try to execute it. In other words, for this to work, if you entered http://othersite/aaa.php in your browser, it should show the PHP source, not the results of processing it.

When passing an URL to include \ require, PHP cannot do anything more than your browser. It's at the mercy of the webserver at othersite. If it doesn't return PHP code, there is no way that PHP can get to it.

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What you are currently doing is getting the remote server to execute the PHP file and then you're reading the parsed contents -- the same as a browser would. So you get (presumably) HTML, not PHP code.

If the remote code does not need to be kept private for any reason (e.g. security) you can get the remote server to serve you the PHP source code. The easiest way to do that is to rename the file as aaa.txt, so it will not be passed to the PHP interpreter.

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You can only do this if the other server is set to serve the PHP files as source -- i.e., without executing them.