GetFilterVersion

The GetFilterVersion function is the first entry-point function called by ISA Server Web proxy on your Web filter. The Web proxy passes a pointer to a HTTP_FILTER_VERSION data structure, which can be used to supply key filter configuration information to the Web proxy. The most important information passed to the Web proxy is the bitmask that contains flags that specify which notification events your filter can process, and a flag that indicates the overall processing priority for your filter. This function must be implemented together with HttpFilterProc.

This function is used to set the notifications that were available to ISAPI filters in ISA Server 2000 and Internet Information Services (IIS). To set the new notifications available in ISA Server 2004, use GetWPXFilterVersion.

The function declaration is:

BOOL WINAPI GetFilterVersion(
  PHTTP_FILTER_VERSION pVer
);

Parameters

pVer

Points to the HTTP_FILTER_VERSION structure that contains both the version information for the server and members with which the filter must indicate filter API version number, and notifications. The priority flags and description field are not used in ISA Server 2004.

Return Values

If this function returns TRUE, the filter will remain loaded. If the function returns FALSE, the filter functionality will be terminated and the filter will be unloaded. If the function returns FALSE in your filter, the filter must call SetLastError with the nature of the failure.

Note  It is important to register only for those notifications that are necessary for your filter's purposes. Registering for additional notifications will reduce performance.

Remarks

At a minimum, a Web filter must implement either GetFilterVersion and HttpFilterProc, or GetWPXFilterVersion and HttpWPXFilterProc (or both pairs of functions).

Requirements

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

See Also

Entry-Point Functions