Ajax long connect using server heart beat to check client connect if it is closed

Using a trick HTTP response header

HTTP/1.1 200 OK
Server: xxx
Beat: Waiting.................................... // trick
Connection:Close
Content-length:255
Content-type:text/xml
Date:Wed Apr 20 12:01:17 EST 2011
Expires:Sun, 24 Apr 1981 01:29:32 GMT

    //PrintStream ps; - Java socket output stream
    private boolean waitForData(String data)
    {
        if (data.equals(""))
        {
            try
            {
                int sleep = 100;
                timer += sleep;
                Thread.sleep(sleep);
                if (timer > 3000) { // check client connection every 3000 ms
                    theLogger.debug("already sleep 3000");
                    if (System.currentTimeMillis() - this.startTime > timeout) { // server timeout
                        return false;
                    }
                    if (!client.isLongConnection) {
                        client.ps.print("HTTP/1.1 200 OK\r\n"); 
                        client.ps.print("Server: xxxx\r\n");
                        client.ps.print("Date: " + (new Date()) + "\r\n");
                        client.ps.print("Expires: Sun, 24 Apr 1981 01:29:32 GMT\r\n");
                        client.ps.print("Beat: Waiting"); // start server beat
                        client.isLongConnection = true;
                    } else {
                        client.ps.print("."); // send fault data
                    }
                    client.ps.flush();
                    
                    if (client.ps.checkError()) { // client closed
                        theLogger.debug("remote client disconnected");
                        return false;
                    }
                    timer = 0;
                }
            } catch (Exception e)
            {
                theLogger.info("waiting update: " + e);
                return false;
            }
            return true;
        } else {
            if (client.isLongConnection) // end server beat
            {
                client.ps.print("\r\n");
                client.ps.flush();
            }
            return false;
        }
    }