The GetFilterVersion function is the first entry point for an ISAPI filter called by IIS. The function tells IIS the version of ISAPI that was used to compile the filter.
BOOL WINAPI GetFilterVersion(
PHTTP_FILTER_VERSION pVer
);
Returns FALSE if the filter will be unloaded and will not receive any notifications.
The GetFilterVersion function, implemented in the ISAPI filter, is the first entry point called by IIS. It is important to specify only the necessary notifications in the pointer to the dwFlags member.
In addition to the notification flags described under the HttpFilterProc function, there are also priority flags to specify the order in which to call the filter. Valid values can be found in the HTTP_FILTER_VERSION structure
HttpFilterProc, HTTP_FILTER_VERSION