The following is a table of notifications for which a Web
(ISAPI) filter can be registered. The notifications are shown in
the order in which they most commonly occur.
| Notification Constant |
Meaning |
| SF_NOTIFY_READ_RAW_DATA |
Occurs when data is being read from the client. May
occur more than once per request. |
| SF_NOTIFY_PREPROC_HEADERS |
Occurs immediately after IIS or ISA has
preprocessed headers, but before the program begins to process
header content. |
| SF_NOTIFY_URL_MAP |
Occurs after IIS has translated a URL to a physical
path on the server. This notification is irrelevant for the ISA Web
proxy service because it does not have any physical URLs. However,
it is provided as it was in Microsoft Proxy Server 2.0, for
compatibility with earlier versions. |
| SF_NOTIFY_AUTHENTICATION |
Occurs just before IIS or ISA authenticates the
client. |
| SF_NOTIFY_AUTH_COMPLETE |
In HTTP authentication scenario, this notification
occurs just after IIS or ISA has determined that access is allowed
for the request resource. |
| SF_NOTIFY_ACCESS_DENIED |
Occurs just after IIS or ISA has determined that
access is denied for the request resource, but before IIS or ISA
has sent a response to the client. |
| SF_NOTIFY_SEND_RESPONSE |
Occurs after the request has been processed by IIS,
but before any headers are sent back to the client. This
notification is not used when the ISA Web proxy service sends a
response. However, it is called when a filter generates a response
itself by using ServerSupportFunction
(SF_REQ_SEND_RESPONSE_HEADERS). |
| SF_NOTIFY_SEND_RAW_DATA |
Occurs as IIS or ISA sends raw data back to the
client. May occur more than once per request. |
| SF_NOTIFY_END_OF_REQUEST |
Occurs at the end of a request. |
| SF_NOTIFY_LOG |
Occurs at the end of a request, just before ISA
writes the transaction to the ISA log. |
| SF_NOTIFY_END_OF_NET_SESSION |
Occurs when a network session with a client is
ending. |
In addition to the notification events, ISAPI makes use of flags
relating to filter priority and port security settings.