Application root directory
The application root directory is the physical directory on your disk the IIS uses as the starting-point for your applications on the web.
You create the application root directory (usually called "ISAPI") in the GAS installation
directory path, for example, $FGLASDIR\ISAPI. You map the application root
directory to a virtual directory or path, typically called "gas", in the IIS configuration. The
virtual directory name is part of application URLs, whereas the physical directory is never part of
your URL.
Note: While IIS allows you to map more than one wildcard application to a
virtual directory, the GAS ISAPI Extension one should be the last on the virtual directory list, as
otherwise it will not forward URLs to other ones.
All requests having an URL that begins with the virtual directory name, for example "/gas/", will be served by the GAS ISAPI Extension. As in the standalone GAS, the GAS ISAPI Extension serves applications configured for the GAS, such as demos, resource files, and static files.
The GAS ISAPI Extension configuration file, isapidispatch.ini, should be the only file present in the application root directory. Files in the application root directory are not served by IIS. There is no way to configure IIS to change this behavior.