http server push

Hello,

I'm trying to implement a server push based communication: a http 
connection remains open as long as possible while the client generates 
content gradually.

I ran into some buffering issues. Here is a toy example:

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
:- http_handler(root(longpoll), longpoll, [time_limit(5)]).

longpoll(Request) :-
         format('Content-type: text/plain~n~n'),
	format('testing~n'),
	sleep(2),
	format('testing~n').
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Expected behavior upon connecting tho /longpoll resource is:

testing
... 2 seconds later
testing

but instead of the above I'm getting:
... 2 seconds delay
testing
testing

Using flush_output/0, ttyflush/0 does not help.

I guess that it has something to do with server-side buffering mentioned 
in sect. 3.1 of the http module documentation 
(http://www.swi-prolog.org/pldoc/package/http.html) saying that:

"The goal is called with the parsed request (see section 3.11) as 
argument and current_output set to a temporary buffer."

However I couldn't find any way to flush this "temporary buffer" - 
assuming that it would help.

Any suggestions?


-- 
Igor Wojnicki