Microsoft Internet Security and Acceleration Server 2004 SDK


The AllocMemoryPerRequest callback function is used to allocate memory (from the process heap to a buffer) per request. Any memory allocated by using this function will automatically be freed by the ISA Server Web proxy at the end of the request (after the SF_NOTIFY_END_OF_REQUEST notification) even if the session continues. For more information on the types of event notifications that are sent to Web filters, see Event Notifications.

If the memory cannot be allocated, this function returns NULL.

The AllocMemoryPerRequest callback function is declared as:

VOID * WINAPI * AllocMemoryPerRequest(
  struct _HTTP_FILTER_CONTEXT* pfc,
  DWORD cbSize,
  DWORD dwReserved


Pointer to the HTTP_FILTER_CONTEXT data structure that is associated with the current, active HTTP session. Pass the filter context in this parameter.
Indicates the size of the buffer to be allocated, in bytes.
Reserved for use by the server.


The AllocMemoryPerRequest function is called through a pointer that is a member of the WPX_FILTER_CONTEXT structure. To get a pointer to the WPX_FILTER_CONTEXT structure for calling the AllocMemoryPerRequest function, use the TO_WPX_FILTER_CONTEXT macro as follows:

if (pwfc != NULL) {


Server: Requires Windows Server 2003 or Windows 2000.
Version: Requires Internet Security and Acceleration Server 2004.
Header: Declared in Wpxhttpfilt.h.

See Also

Callback Functions