(define (fcgi-handler-responder socket req content-length)

 ; this does the fcgi dance involving multiplexing the stdin, stdout and stderr
 ; streams over the socket. We have to make that the socket doesn't deadlock.
 ; Deadlock will occur if we let the FCGI script fill up all the buffers and we
 ; neglect to read anything before sending data.
 (define (in-out-dance #!optional (data #f))
  (printf "\nDancing.\n")
   (let ((messages (if data
		     (read/write-socket socket 1 fcgi-stdin data)
		     (read/write-socket socket 1 #f))))
     ; process the messages
     (pp messages)
     ; Quick hack so we can see something working
     (let ((stdout (alist-ref fcgi-stdout messages)))
       (if (and stdout (> (blob-size (car stdout)) 0))
	 (send-response status: 'ok body: (blob->string (car stdout)))))

     ;   when it starts, sort out the headers: remove content-length and close? if content length is not supplied then close?
     ;   transfer it to the spiffy response port or log it to debug-log as it arrives.
     (printf "That dance is over.\n")
     (if (alist-ref fcgi-end-request messages) #t #f)
     )
   )

  ;(read/write-socket socket request-id type . args)

  ; send fcgi-begin-request
  (read/write-socket socket 1 fcgi-begin-request fcgi-responder)
  ; send fcgi-params
  (read/write-socket socket 1 fcgi-params (cgi-build-env req "!!!FIXME!!!"))
  (read/write-socket socket 1 fcgi-params 'close-stream)

  ; stream request data over fcgi-stdin.
  (copy-port (request-port req) in-out-dance content-length)
  (let loop ((done? (in-out-dance 'close-stream))) ; wait for all the replies to come back
   (if (not done?) (loop (in-out-dance)))))