Sending Response Headers from ISAPI Extensions
Before an ISAPI extension delivers any output in response to a client request, it must send the client an HTTP response header. Among other things, the response header specifies the type of content being returned to the client, and whether the connection should be kept active after the request is serviced. The header must have the correct format or the client will be unable to use it.
A response header is sent using the ServerSupportFunction with the HSE_REQ_SEND_RESPONSE_HEADER_EX parameter, which replaces the HSE_REQ_SEND_RESPONSE_HEADER parameter and uses the HSE_SEND_HEADER_EX_INFO structure to specify the header information.