Last week I attended a day of outstanding geek fun . At the Google wave hackathon I had the chance to sink my teeth into the Google wave API after seeing presentations on gwt and google wave by Tommy Pedersen and a presentation on wave gadgets by Joakim Recht.
After a couple of hours of presentations and brainstorming we started hacking. I teamed up with skakanka to experiment with sending the contents of a wave to a Proof of concept Document storage system . But we ended up doing a simple Echo Bot (but hey! we illustrated how to extract content from a wavelet and send it somewhere).
I brought a mac and used the Google eclipse plugin for galileo for coding. It helped that I allready had a Google app engine account from some earlier experiments – but I spent some time learning the different key combinations on the mac – it was great fun though (and now I know how to use eclipse on a mac!). Deploying on google app engine is as simple as pressing a button in eclipse (I also tried using som ant tasks in my earlier experiments).
We managed to have a google wave running sometime before lunch – so it is very easy to get a basic understanding what a wave bot is all about. (You could think of it as an ircbot on steroids ! )
The overall idea of building a google wave bot is to listen to incoming events defined in the protocol. Let’s say we want to perform something when somebody enters the wave or write something – then we can define the capabilities like this:
Then the robot should act on the defined events in a manner similar to this :
@Override
public void processEvents(RobotMessageBundle robotMessageBundle) {
Wavelet wavelet = robotMessageBundle.getWavelet();
String rootText = wavelet.getRootBlip().getDocument().getText();
for ( Event e: robotMessageBundle.getEvents()){
Blip b= e.getBlip();
String text= e.getBlip().getDocument().getText();
if (e.getType().equals(EventType.BLIP_SUBMITTED)){
e.getBlip().getDocument().append( makeEcho(text));
}
}
}
The Wave client api offers something like the DOM api for the xml being sent back and forth. During the hackathon I learnt that there is no way to ask for the contents of the entire wave from a single blip – so it will require some thinking to save the entire contents of the wave – but it should be doable.
Sometime during the afternoon things started to slow down on the wave test server. I noticed that some of the other guys doing a multiuser interactive drawing gadget for wave. It looked like they recorded a delta to send every time the mouse moved! This made me want to look a bit under “the hood”:
Sounds like the team are handling the multiuser issues using “operational transforms” . Maybe they could somehow ‘batch’ deltas from interactive gadgets ? I have yet to fully understand how “operational transforms” work – but it sounds like an exciting challenge to make this work on a large scale!
