Build Widgets

Anatomy of a Widget
• Config.xml <- W3C Widgets P&C Spec
• icon.png
• index.html <- HTML start file
• JavaScript code, CSS

• Zip it up, change ext to .wgt, and you’re
done

Widget metadata
• Id
• Height, Width
• Name
• Description
• Version
• Features
• Author info
• License

A Silly Example: config.xml
<?xml version="1.0" encoding="utf-8"?>
<widget xmlns="http://www.w3.org/ns/widgets"
id="http://www.getwookie.org/widgets/tea"
version="1.0” height="150” width="125">
<name>Tea</name>
<description>A silly Tea widget</description>
<author>Scott Wilson</author>
</widget>

A Silly Example: index.html
<html>
<body>
<img src="tea.jpg" />
<p>Time for a break, mate</p>
</body>
</html>

Make your own basic widget
1. Make an index.html file
2. Make a config.xml file
3. Zip them up, and change suffix to “.wgt”
4. Upload to a wookie server

Uploading
• Go to http://192.168.2.161/wookie
• Click “admin”
• Login with java/java
• Click “add new widget”
• Find your .wgt file
• OK!

Previewing a widget
• Go to 192.168.2.161:8080/wookie
• Click “View Widget Gallery”
• Click the “demo” link under your widget
• Your widget will show

Preferences
• You can store preferences for an instance of
a widget using:

widget.preferences.setItem(“key”, “value”)
widget.preferences.getItem(“key”)

Collaborative Widgets
• State and Participants

• State is shared across widgets with the same
IRI in the same shared context.
• State is propagated to related widgets using
an event callback
• State is set by submitting deltas

State example
wave.setStateCallback(stateUpdated);

stateUpdated = function(){
var keys = wave.getState().getKeys();
for (var i = 0; i < keys.length; i++) {
alert(wave.getState().get(keys[i]));
}
};

wave.getState().submitValue(“key”, “value”);

Participants
• Register callbacks with:
wave.setParticipantCallback(myfunction);

• Methods:
– getViewer() - get the current user
– getParticipants() - get map of all participants

• Model:
– getId(), getDisplayName(), getThumbnailUrl()

Making a collaborative app
• This requires some more planning

1. Draw up a design
2. Create a working test page
3. Implement models, action handlers and
event handlers
4. Create the config.xml, icon.png, zip it up
and run it

Design
• Start with the view - what the widget looks
like
• Create the model - what are the objects in
the state model?
• Add the actions - how you interact with it
• Wire it all up…

Prototyping
• Make a regular html page to test out your
view. Populate it with fake model, and don’t
wire up the actions yet
• You can reuse this for the real widget - just
take out your fake state info sections

Implementing
• Create a “Model” object for your state
model
• Create a “Controller” object, and a method
in it for each action
• Register the participant and state event
handlers with an “update view” method that
populates the view when running

Models
• Models can be implemented in typical “bean” fashion
• Save/Find methods need to access wave state
• Can use JSON (e.g. with json.js) or just plain strings for storage

function Task(id,name,status,assigned){
this.task_id = id;
this.name = name;
this.status = status;
this.assigned_to = assigned;
}
Task.prototype.save = function(){
wave.getState().submitValue(this.task_id, JSON.stringify(this));
}

Static model methods
Task.create = function(json){
var obj = JSON.parse(json);
var task = new Task(obj.task_id,
obj.name,obj.status,obj.assigned_to);
return task;
• Typically need
}
methods to turn state
Task.find = function(task_id){
for (var i = 0; i < keys.length; i++) {
strings back into
var key = keys[i];
if (key == task_id){
model instances
return Task.create(task_id, wave.getState().get(key));

}
} • Also finder methods to
}
return null;
get a particular model
Task.findAll = function(){ object
var tasks = {};
for (var i = 0; i < keys.length; i++) { • This isn’t the only way
var key = keys[i];
var task = Task.create(key, wave.getState().get(key));
tasks[key] = task;
to do this, but is an
}
return tasks;
OK pattern
}

Controllers
/**
* The Controller object
* This is used to wire up the view and model with actions
• Methods for each
*/
var Controller = {
action, making
// Action handlers changes to the model
// Toggle task state between completed and to-do
toggleTask: function(task_id){
• You usually don’t
},
need to do any code
// Create a new task
newTask: function(){
},
that interacts with
// Abandon task for someone else to do
HTML, as the event
abandonTask: function(task_id){
}, handlers should do
// Claim a task (assign to self)
claimTask: function(task_id){
that
}
}

Event Handlers
// Update the view when state has been updated These fire whenever the state or participants
stateUpdated: function(){ are updated (e.g. by another instance).
var tasks = Task.findAll();
if (tasks && tasks != null){
var tasklist = ""; Event handlers need to be registered like so:
for (key in tasks) {
var task = tasks[key]; wave.setStateCallback(Controller.stateUpdated);
wave.setParticipantCallback(Controller.participantsUpdated);
tasklist += // the task stuff to show
dwr.util.setValue("tasklist", tasklist, {
escapeHtml:false }); Also useful to have these methods called
var objDiv = document.getElementById("tasklist"); from onLoad() in an init() function to
objDiv.scrollTop = objDiv.scrollHeight; create initial view
}
},
participantsUpdated: function(){ You can import JQuery if you like for
Controller.updateUser(); setting the view content, or do it using
} DOM

Packaging
You need to add this to your config.xml to tell
Wookie to include the Wave Gadget API
methods:

<feature
name="http://wave.google.com"
required="true"/>

Uploading, debugging and testing
• You need a • I’ve set up a Moodle
collaborative instance at:
environment to test
your widget properly 192.168.2.XXX

Login as ws1,ws2,ws3,
or ws4

Other stuff…
• AJAX • Camera access
If you want to call If you want to access the
external sites from user’s camera from a
within the widget, call widget, there is an
myurl =
example of how to do
widget.proxify(url)
first to call it via proxy. this in the moodle
Also need to add the course (topic 3)
site to the server
whitelist.

Build Widgets

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