Google Wave Gadgets API & GWT

GWT

Google Wave

Gadgets API

Wave Gadget

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Wave Gadgets API

Gadgets API

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XML

state callback

state delta

CSS

HTML

state:

vote-douwe@google.com | 1

JS

State Delta

function onClick() {

wave.getState().submitValue('vote-' wave.getViewer().getId(), -1);

}

State Callback

wave.setStateCallback(update);

function update() {

var keys = wave.getState().getKeys();

for (var i = 0; i < keys.length; i++) {

var key = keys[i];

if (key.match('^vote-')) {

total += parseInt(wave.getState().get(key));

count++;

}

}

document.getElementById('total').innerHTML = total;

}

Mini Webpage

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Shared State

Collaborative Web App

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import org.cobogw.gwt.waveapi.gadget.client.StateUpdateEvent;

import org.cobogw.gwt.waveapi.gadget.client.StateUpdateEventHandler;

import org.cobogw.gwt.waveapi.gadget.client.WaveGadget;

import com.google.gwt.event.dom.client.ClickEvent;

import com.google.gwt.event.dom.client.ClickHandler;

import com.google.gwt.gadgets.client.Gadget;

import com.google.gwt.gadgets.client.UserPreferences;

import com.google.gwt.user.client.ui.Button;

import com.google.gwt.user.client.ui.Label;

import com.google.gwt.user.client.ui.RootPanel;

@Gadget.ModulePrefs(title = "PlusOne")

public class SimpleCounter extends WaveGadget<UserPreferences> {

private final Label counterLabel = new Label();

private final Button incrementButton = new Button("+1");

private final Button decrementButton = new Button("-1");

@Override

protected void init() {

// Event handlers for increment and decrement buttons

// First they update the local counter's value to the new value

// and then they store the new value in wave's shared state

incrementButton.addClickHandler(new ClickHandler() {

public void onClick(ClickEvent event) {

String viewer = getWave().getViewer().getId();

getWave().getState().submitValue(viewer, '1');

}

});

decrementButton.addClickHandler(new ClickHandler() {

public void onClick(ClickEvent event) {

String viewer = getWave().getViewer().getId();

getWave().getState().submitValue(viewer, '1');

}

});

// Adding the ui elements to the root panel

RootPanel.get().add(counterLabel);

RootPanel.get().add(incrementButton);

RootPanel.get().add(decrementButton);

getWave().addStateUpdateEventHandler(new StateUpdateEventHandler() {

public void onUpdate(StateUpdateEvent event) {

int total = 0;

JsArrayString keys = getWave().getState().getKeys();

for (int i = 0; i < keys.length(); i++) {

String key = keys.get(i);

String value = getWave().get(key);

total += (int) value;

}

counterLabel.setText(total);

}

});

}

}