ISAPI

[Anon]

I'm working on a text about web applications and have now come across the implementation of PHP in the IIS.
So I played around a bit with the server to find out that if I've added the PHP-ISAPI filter, the page is proceeded in the inetinfo-process, if it's removed, the dllhost does the work, so I expect the page to be processed out of process by the isapi-extension.
But I'm NOT sure about that.
So if anyone knows, please tell me
- when are the extensions and when the filters used
- how can I define if the extension should run in process or out process
- how does Apache manage this? Does it simply load the libraries and runs them in proces?

Thanks for any answers.