Server Push support will be standardized in Servlet 3.0. JEE6 servlet containers, will be Comet enabled thanks to JSR 315: http://jcp.org/en/jsr/detail?id=315

when add some sample code of GWT-RPC for server push??

Or if you wish to use a working comet implementation today built ontop of a regular servlet you can try rocket-gwt Comet feature. Refer to the wiki for further details. Wiki: http://code.google.com/p/rocket-gwt/wiki/Comet Download: http://code.google.com/p/rocket-gwt/downloads/list

http://groups.google.com/group/Google-Web-Toolkit/browse_thread/thread/5e851d1b960e303e/4f58a36d88f8eaca#4f58a36d88f8eaca

shows a solution for server push with GWT and the Tomcat CometProcessor?.

The development of the code has stopped for the moment, but it worked at least once.

just finishing PHP based web server with "continuations" support, Gwt-Php framework will be released by end of this year. (www.gwtphp.com currently in construction)

how about integrating GWT with 3rd party server push libraries/frameworks like DWR? Check http://code.google.com/p/dwr4gwt

The GWTEventService also is working great! It doesn't need just Jetty or Tomcat, but works on both webservers independently.

http://code.google.com/p/gwteventservice/

Here is a GWT comet implementation I've built:

http://code.google.com/p/gwt-comet/

The library implements Comet by streaming messages over long lived HTTP requests to minimise latency and bandwidth requirements and maximise the throughput. This is opposed to many other implementations which use polling or long polling techniques.

Isn't this similar to BOSH, also known as httpbind?

FYI: StreamHub? has an open source GWT server push adapter:

http://www.stream-hub.com/

stream hub is paid

can you do server push on Google App Engine? Is there a good example project that shows how it can be done?

not yet

I have this solution working using blockingDequeue, but i've not yet tested abusive scenarios... this serves a need for a lowl latency gui update on a localhost kiosk servlet

client package

public interface KioskEvent extends Serializable{
}
public class PopupEvent implements KioskEvent {
    private String message;
 
    public PopupEvent(String message) {
        this.message = message;
    }
 
    public PopupEvent() {
    }
 
    public String getMessage() {
        return message;
    }
}

    Timer parkTimer= new Timer() {
                    @Override
                    public void run() {
 
                        park();
 
                    }
                };

    public void onModuleLoad() {
 [....] 
       park();
 
    }
 
    public void park() {
    PushProvider.App.getInstance().eventWait(new AsyncCallback<Collection<KioskEvent>>() {
            @Override
            public void onFailure(Throwable caught) {
                parkTimer.schedule(5000);
            }
 
            @Override
            public void onSuccess(Collection<KioskEvent> result) {
                for (Iterator<KioskEvent> iterator = result.iterator(); iterator.hasNext();) {
                    KioskEvent kioskEvent = iterator.next();
                    iterator.remove();
                    if (kioskEvent instanceof PopupEvent) {
                        PopupEvent popupEvent = (PopupEvent) kioskEvent;
                        Window.alert(popupEvent.getMessage());
                    }else if(kioskEvent instance of [...]) {[...]}
                }
                parkTimer.schedule(1);
            }
        });
    }

RPCServlet

public class PushProviderImpl extends RpcServlet implements PushProvider, PopupHandler {
 

    {
        final java.util.Timer timer = new Timer() ;

        timer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                popup("test");
            }
        }, 5000, 60000);
    }

    BlockingDeque<KioskEvent> dq = new LinkedBlockingDeque(3);
 
    @Override
    public Collection<KioskEvent> eventWait() {
        final LinkedList<KioskEvent> list = new LinkedList<KioskEvent>();
        do {
            try {
                list.add(dq.takeFirst());
            } catch (InterruptedException e) {
 
            }
        } while (!dq.isEmpty());
        return list;  //To change body of implemented methods use File | Settings | File Templates.
    }
 

    @Override
    public void popup(String message) {
        dq.add(new PopupEvent(message));
    }
}