ServerSupportFunction callback function

Applies to: desktop apps only

The ServerSupportFunction callback function extends the Web filter functions. Parameters are specific to the extensions. The ServerSupportFunction callback function can be used by Web filters to accomplish a wide variety of tasks.

The ServerSupportFunction callback function is declared as:


BOOL WINAPI ServerSupportFunction(
  struct _HTTP_FILTER_CONTEXT pfc,
  enum SF_REQ_TYPE sfReq,
  PVOID pData,
  ULONG_PTR ul1,


  • pfc
    Pointer to the HTTP_FILTER_CONTEXT data structure that is associated with the current, active HTTP session. Pass the filter context in this parameter.

  • sfReq
    Specifies the particular support function that is to be executed by the Forefront TMG Web filter.

  • pData
    See Remarks.

  • ul1
    See Remarks.

  • ul2
    See Remarks.


The pData, ul1, and ul2 parameters are described in the individual support function sections. See the following list:


If a parameter is designated as unused for a particular support function, you should set the parameter to NULL or 0, as appropriate.

SF_REQ_GET_CONNID is not supported by Forefront TMG or by Internet Information Services (IIS) 6.0, IIS 5.0, or IIS 4.0 and will return 0.

SF_REQ_GET_PROPERTY is not supported by Forefront TMG and will return 0.

SF_REQ_SET_PROXY_INFO is not used in the Forefront TMG implementation of ISAPI.

SF_REQ_SET_NEXT_READ_SIZE is not relevant to the implementation of ISAPI in Forefront TMG. It is provided for compatibility with IIS.

For more information about the types of event notifications that are sent to Web filters, see Event Notifications.


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

Callback Functions



Build date: 7/12/2010