com.vaadin.ui
Annotation Type ClientWidget

@Retention(value=RUNTIME)
@Target(value=TYPE)
public @interface ClientWidget

Annotation defining the default client side counterpart in GWT terminal for Component.

With this annotation server side Vaadin component is marked to have a client side counterpart. The value of the annotation is the class of client side implementation.

Note, even though client side implementation is needed during development, one may safely remove them from the classpath of the production server.

Since:

6.2

Required Element Summary

Class<? extends Paintable>

value

Optional Element Summary

ClientWidget.LoadStyle

loadStyle Depending on the used WidgetMap generator, these optional hints may be used to define how the client side components are loaded by the browser.

Element Detail

value

public abstract Class<? extends Paintable> value

Returns:

the client side counterpart for the annotated component

loadStyle

public abstract ClientWidget.LoadStyle loadStyle

Depending on the used WidgetMap generator, these optional hints may be used to define how the client side components are loaded by the browser. The default is to eagerly load all widgets EagerWidgetMapGenerator, but if the WidgetMapGenerator is used by the widgetset, these load style hints are respected.

Lazy loading of a widget implementation means the client side component is not included in the initial JavaScript application loaded when the application starts. Instead the implementation is loaded to the client when it is first needed. Lazy loaded widget can be achieved by giving ClientWidget.LoadStyle.LAZY value in ClientWidget annotation.

Lazy loaded widgets don't stress the size and startup time of the client side as much as eagerly loaded widgets. On the other hand there is a slight latency when lazy loaded widgets are first used as the client side needs to visit the server to fetch the client side implementation.

The ClientWidget.LoadStyle.DEFERRED will also not stress the initially loaded JavaScript file. If this load style is defined, the widget implementation is preemptively loaded to the browser after the application is started and the communication to server idles. This load style kind of combines the best of both worlds.

Fine tunings to widget loading can also be made by overriding WidgetMapGenerator in the GWT module. Tunings might be helpful if the end users have slow connections and especially if they have high latency in their network. The CustomWidgetMapGenerator is an abstract generator implementation for easy customization. Vaadin package also includes LazyWidgetMapGenerator that makes as many widgets lazily loaded as possible.

Returns:

the hint for the widget set generator how the client side implementation should be loaded to the browser

Since:

6.4

Default:

DEFERRED