Applies to: desktop apps only

The Forefront TMG Web proxy includes a pointer to the WPX_FILTER_PREPROC_HEADERS structure in the notification that it sends to Web filters when it preprocesses a request's headers or a Web server response's headers. If your filter should be notified for this event, it must register to receive SF_NOTIFY_PREPROC_HEADERS or SF_NOTIFY_RECEIVE_RESPONSE_HEADERS notifications. For more information about the types of event notifications that are sent to Web filters, see Event Notifications.


  BOOL (WINAPI) *GetHeader;
  BOOL (WINAPI) *SetHeader;
  BOOL (WINAPI) *AddHeader;
  DWORD         HttpStatus;
  DWORD         dwReserved;
  BOOL (WINAPI) *SetUserCachingKey;


  • GetHeader
    Pointer to the GetHeader callback function, which can be used to retrieve a specified header, a portion of the request line in the request, or the status from the response. Header names include a trailing colon (:). Individual portions of the request line are specified by the special values "body" (for requests only), "method", "URL", and "version". The status from the response line is specified by the special value "status". The special values are case-sensitive and must not include the trailing colon.

  • SetHeader
    Pointer to the SetHeader callback function, which can be used to modify or delete the value of a header or to modify a portion of the request line or the response line that is specified by a special value.

  • AddHeader
    Pointer to the AddHeader callback function, which can be used to add an HTTP header to the response.

  • HttpStatus
    Not used.

  • dwReserved
    A DWORD reserved for later use.

  • SetUserCachingKey
    Sets the user caching key.


When the server is about to process the client headers, it sends a notification by calling the HttpFilterProc entry-point function of each Web filter that is registered to receive the notification. The pvNotification parameter contains a pointer to an WPX_FILTER_PREPROC_HEADERS structure, and the notificationType parameter is set to SF_NOTIFY_PREPROC_HEADERS.


Minimum supported client

None supported

Minimum supported server

Windows Server 2008 R2, Windows Server 2008 with SP2 (64-bit only)


Forefront Threat Management Gateway (TMG) 2010



See also

Notification Structures



Build date: 7/12/2010