This support function can be used to disable specific notification types for your ISAPI filter, for the remaining lifetime of that request. If a particular notification event is disabled for your filter, then IIS will not call your filter when that notification event occurs.
New requests will generate the notifications for which your filter registered when it was loaded.
BOOL WINAPI * ServerSupportFunction(
PHTTP_FILTER_CONTEXT pfc,
enum SF_REQ_TYPE SF_REQ_DISABLE_NOTIFICATIONS,
PVOID pData,
DWORD ul1,
DWORD ul2
);