BigPipe.java

## BigPipe.java
public class BigPipeServlet extends HttpServlet {

    private static ExecutorService executor = Executors.newFixedThreadPool(500, new ThreadFactory() {
        public Thread newThread(Runnable r) {
            Thread t = new Thread(r);
            t.setName("Service Thread "+ t.getId());
            t.setDaemon(true);
            return t;
        }
    });

    protected void service(HttpServletRequest req, final HttpServletResponse resp) throws ServletException, IOException {
        final PrintWriter writer = resp.getWriter();

        String doctype = "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Strict//EN\"\n" +
                "   \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd\">";

        String head = "<html xmlns=\"http://www.w3.org/1999/xhtml\" xml:lang=\"de\" lang=\"de\"> \n" +
                "<head> \n" +
                "<meta http-equiv=\"Content-type\" content=\"text/html; charset=utf-8\" /> \n" +
                "<meta http-equiv=\"Content-language\" content=\"de\" />\n";

        writer.write(doctype);
        writer.write(head);
        writer.write("<script type=\"text/javascript\">function arrived(id,text) { var b=document.getElementById(id); b.innerHTML = text; }</script>");
        writer.write("</HEAD><BODY><div>Progressive Loading");

        content(writer, "content1", "content2", "content3", "content4", "content5", "content6");
        writer.write("</div>\n");

        final Random random = new Random();

        List<Callable<Boolean>> tasks = new ArrayList<Callable<Boolean>>();

        for (int i = 0; i < 6; i++) {
            final int id = i + 1;
            tasks.add(new Callable<Boolean>() {
                public Boolean call() {
                    try {
                        // One service call is nasty and takes 50sec
                        if (id == 3) {
                            Thread.sleep(50000);
                        } else {
                            Thread.sleep(random.nextInt(2000));
                        }
                        pagelet(writer, "content" + id, "Wohooo" + id);
                    } catch (InterruptedException e) {
                        return false;
                    }
                    return true;
                }
            });
        }

        try {
            executor.invokeAll(tasks, 1500, TimeUnit.MILLISECONDS);
        } catch (InterruptedException ignored) {
            // ignored
        }
        writer.write("</BODY></HTML>");
    }

    private void content(PrintWriter writer, String... contentIds) {
        for (String id : contentIds) {
            writer.write("<div id=\"" + id + "\">-</div>\n");
        }
    }

    private void pagelet(PrintWriter writer, String id, String content) {
        if (writer.checkError()) return;
        writer.write("<script>" +
                "arrived(\"" + id + "\", \"" + content + "\");" +
                "</script>\n");
        writer.flush();
    }
}