Handling.java

	private BlockingQueue<String> messages = new LinkedBlockingQueue<String>();
	private AtomicInteger counter = new AtomicInteger();

	protected void doPost(HttpServletRequest req, HttpServletResponse arg1)
			throws ServletException, IOException {
		System.out.println("sending a message to all clients");
		messages.add(String.format("sending message number %d %n", counter.incrementAndGet()));
	}

queue.java

	private Queue<AsyncContext> clients = new ConcurrentLinkedQueue<AsyncContext>();

	protected void doGet(HttpServletRequest req, HttpServletResponse arg1)
			throws ServletException, IOException {
		AsyncContext ctx = req.startAsync();
		ctx.setTimeout(3000000); 
		clients.add(ctx);
		System.out.println("new client connected." );
	}

run.java

public void run() {
	while (true) {
		final String message = messages.take();
		for (final AsyncContext ctx : clients) {
			public void run() {
				PrintWriter writer = ctx.getResponse().getWriter();
				writer.println(message);
				writer.flush();
			}
		}
	}
}

servlet.java

@WebServlet(urlPatterns = { "/subscribe" }, asyncSupported = true)
public class ChatServlet extends HttpServlet {