Building W3C widgets on the Wookie training day

Last week OSS Watch organised its first training day in Oxford. We got together with about 15 people to gain hands-on experience with Apache Wookie (Incubating). Wookie provides an implementation of the W3C widget specifications, so a lot of emphasise was put on building these kinds of widgets. We succeeded quite well in getting to know the spec and how to build widgets and ended the day with a nice collection of newly built widgets and even a submitted patch to the Wookie source code.

Scott Wilson, the Wookie guru from Bolton University, where it all started, started the day off with a presentation (pdf) of what widgets and Wookie are all about. Widgets are basically small mini applications that are designed to work in a small view area. Many platforms have created their own format for it, but the W3C is working on a set of specifications for it with a consortium of partners from both traditional computing and mobile platforms, which will lead to a true cross-platform standard which will hopefully lead to widespread adoption. A minimal W3C widget consists of nothing more than a config file and an HTML file, zipped up as an archive with file extension .wgt. The config file contains basic configuration such as the name, description and preferred dimensions of the widgets. The widget can furthermore include as much HTML, CSS, images and JavaScript files as one would like.

Apache Wookie (Incubating) is an application that provides a W3C-compliant widget server. You can use Wookie to deploy widgets and you can serve W3C widgets from the Wookie server in third party applications. Plugins have already been written for Moodle, LAMS, Sakai and Google Wave. Wookie also has a REST API that can be used to get, or create widgets.

After Scott’s intro it was time to get dirty. Ross handed out CDs containing the latest sourcecode of Wookie (which can be downloaded by anybody from Subversion) and prerequisites like a JDK and Apache Ant. His presentation (pdf) was about ‘how to build your first widget’. I was surprised to see that there were 10 people with Mac-books in the room, amongst 4 Windows machines and one Linux netbook. Apple surely knows how to impress the developer these days! After some initial troubles with environment settings etc. most people got up-and-running fairly quickly and were ready to build their first widget. Wookie provides handy Ant tasks for building and deploying widgets, which means that generating a hello-world skeleton widget is as easy as typing ant seed-widget and answering some questions about the name, description and dimensions of your widget. After you have started up the Wookie server using ant run you can deploy the widget using ant deploy-widget. That was it, quite easily. I must say, having moved away from Ant and using Maven2 for the last few years, it’s nice to be remembered of the powerful features Ant has to offer. Especially since Wookie uses Ant in combination with Apache Ivy, the dependency management alternative for Maven2. (To be precise, you can also use Ivy with Maven2 repositories). Ross also demonstrated how you can make use of OpenStreetMap JavaScript APIs to embed cool navigational features in your widget quite easily. You can check out his presentation (pdf) or directly check out the source code of the tutorial including the example JavaScript.

In his second presentation (pdf) Scott focussed on some design principles behind the widget specification and gave a walk-through of how you can design a more advanced widget by making use of features of the W3C widget object API and integrate with the Google Wave Gadgets API. No Wave server is needed to get this working, as Wookie can handle everything for you. Scott demonstrated a Task widget with collaboration features, that can be used by different users concurrently using State and Participants.

After the break it was high time for everybody to create their own widget and some interesting ideas had come up. One of us decided it would be much cooler to hack directly in the server code instead of building widgets and he submitted a patch to Wookie to allow hot deployment of a widget to ease the development/deployment cycle. That’s very cool, thanks Matthew!

The rest of us built some widgets for a wide variety of purposes. One of the nice things about the widgets was that we could easily merge them all together on one Wookie instance and show all widgets there. These were some of the widgets that resulted from this 1.5 hour hack-fest:

  • Video player embedded in a widget with fallback to other formats depending on the user agent
  • Display a list of links using output from one of the Yahoo pipes
  • Display the last.fm playlist of a user and show what that user is currently listening to
  • Show a canvas drawing where multiple people can collaborate by working on the same drawing using HTML5
  • Cool kids’ game where the user can name his pet dinosaur
  • Currency converter that (eventually) would use an external currency conversion provider

It was fun to see how easily you can create functional widgets. If you make use of external JavaScript APIs or data feeds it is also quite simple to create a useful (or not so useful…) widget. This was a nice conclusion of the day and seeing all the widgets we had created we thought we had deserved our beer and headed off to the pub. Thanks to Scott and Ross for making this a successful Wookie training day!

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