org.wicketstuff.push
Interface IPushService

All Superinterfaces:

java.io.Serializable

All Known Implementing Classes:

TimerPushService

public interface IPushService
extends java.io.Serializable

A push service provides a simple way to install push facility on a component, and then push events to the component using a IPushTarget.

Implementations of IPushService must be thread safe, and thus easily reusable.

Here is a common example of usage:

 private static final IPushInstaller PUSH_INSTALLER = new IPushInstaller() {
   public void install(Component component, final IPushTarget pushTarget) {
     myServerEventService.addListener(new MyListener() {
                public void onEvent(Event ev) {
                if (pushTarget.isConnected()) {
                                pushTarget.addComponent(myComponentToUpdate);
                                pushTarget.appendJavascript("alert('event received from server:"+ev+"');");
                                pushTarget.trigger();
                        } else {
                                myServerEventService.removeListener(this);
                        }
                }
     });
   }
 }

 ...

 pushService.installPush(myComponent, PUSH_INSTALLER);
 

Using a unique instance of push installer is highly recommended, since it is then referenced in the Wicket Application (using a different instance each time could thus lead to a memory leak). If you need to pass different instances each time, you are responsible for calling uninstallPush on the component to free the reference to the installer.

This service is usually used when you already have a facility for triggering and listening server side events that you want to propagate to the clients.

For a mechanism including an event publish/subscribe mechanism, see IChannelService

Author:

Xavier Hanin

See Also:

IChannelService, IPushInstaller

Method Summary

IPushTarget	installPush(org.apache.wicket.Component component) Installs a push facility on the given component.
void	uninstallPush(org.apache.wicket.Component component) Uninstalls a push installer which has previously been installed on a component.

Method Detail

installPush

IPushTarget installPush(org.apache.wicket.Component component)

Installs a push facility on the given component.

The component on which the push facility is installed doesn't really matter as soon as it is visible, except that only one push service can be installed by component.

Usually the page is used as component.

Parameters:

component - the component on which the push facility must be installed

uninstallPush

void uninstallPush(org.apache.wicket.Component component)

Uninstalls a push installer which has previously been installed on a component.

Calling this method after calling #installPush(Component, IPushInstaller) is mandatory if you use a different push installer instance for each component instance.

Parameters:

component - the component on which push service must be uninstalled