id	summary	reporter	owner	description	type	status	priority	milestone	component	resolution	keywords	cc	planetversion	pltversion
188	Not a ticket for this component, but the request enhancement for the web server	anonymous	jaymccarthy	"Hello!  Sorry for this 'transit-request' post.
Please move following enhancement ticket to the web server team.

The current make-response/incremental (in response.ss) has two
disadvantages: 1st can lead to browser-confusing chunked response
with zero chunk lengths, and the 2nd freezes the Comet (javascript
technology) programming - there is no way to flush out selected
chunks during paused response/incremental (with sleeps).

Please consider following patch, which should eliminate both issues. It interprets zero-length chunk simply as `flush-output' request for previous chunks. Comet now runs well using 
'(do-loop (wait-and-send-next-event) (send/bytes #""""))' pattern. 

 --- collects/web-server/http/response.ss.orig   2009-06-05 10:40:07.747989122 +0400
+++ collects/web-server/http/response.ss        2009-06-05 10:57:55.674988779 +0400
@@ -110,10 +110,13 @@
          (begin
            ((response/incremental-generator bresp)
             (lambda chunks
-              (fprintf o-port ""~x\r\n""
-                       (apply + 0 (map bytes-length chunks)))
+              (let ((len (apply + 0 (map bytes-length chunks))))
+                (if (= 0 len) ; Protects against zero-length-chunk bug
+                     (flush-output o-port) ; ... and makes Comet happy
+                     (begin
+                       (fprintf o-port ""~x\r\n"" len)
               (for-each (lambda (chunk) (display chunk o-port)) chunks)
-              (fprintf o-port ""\r\n"")))
+                       (fprintf o-port ""\r\n""))))))
            ; one \r\n ends the last (empty) chunk and the second \r\n ends the (non-existant) trailers
            (fprintf o-port ""0\r\n\r\n"")))]))

"	enhancement	closed	minor		untyped/dispatch.plt		web server response incremental comet		(2 1)	4.2