Call this method to empty the response buffer and send its current contents to the client.
TRUE if this is the final time Flush will be called.
Returns TRUE on success, FALSE on failure. Call GetLastError to get extended error information.
Any headers that have been set in the response will be sent just before the data is written to the client if no headers have been sent up to that point.
If bFinal is TRUE, if the response is buffered, and if the client is communicating using HTTP 1.1, Flush will add a Connection: Keep-Alive header and a Content-Length header to the response.